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v ijibrary 



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33CENTS 




How to Build a Two-Stage Radio-Frequency Amplifier 

THE MARCH OF RADIO* ub ^ n L s ^c^ 
. New Method of Transmitting Pictures by Wire or Radio 



N 



OUBLEDAY, PAGE & COMPANY 



GARDEN CITY, NEW YORK 



Two Strikes 
Three Balls! 

The pitcher has com- 
pleted that slow, leisure- 
ly, tantalizing wind-up. 
That long, lithe, million 
dollar arm has flashed 
back. A moment . . . 
and the ball, a white, hissing 
streak, is catapulting toward 
the catcher's waiting mitt. 
And the winning or losing of 
a World Series depends on 
whether or not the batter has 
his eye on the ball. 





A Cunningham Tube always has 
its eye on the ball. It stands ready 
to transmute an electrical impulse, 
traveling at a speed which would 
make the speed of a baseball seem 
a snail's pace, into music, a Pres- 
ident's message what you will. 



Since 1915- 

Standard for All Sets 



Types C-301A: C-299: C-300: C-ll: C-12, In the orange and 
blue carton. 

Price $3.00 each 



RADIO /y TUBES 




Patent Notice: Cunningham tubes are covered by patents dated 2-18-08. 2-18-12. 12-30-13. 10-23-17. 10-23-17 and others issued and pending 



^ Tested and approved by RADIO BROADCAST if 

Bound OEC 1 1921 



RADIO BROADCAST 



VOLUME VII 

MAY, 1925, to OCTOBER, 1925 



BETTER RADIO 




GARDEN CITY NEW YORK 

DOUBLEDAY, PAGE & COMPANY 

1925 



Copyright, 1925, by 
DOUBLEDAY, PAGE & COMPANY 



RADIO 
BROADCAST 



Vol. 7, No. i 




May, 



A New Method of Transmitting 
Pictures by JVire or Radio 



A Review of Existing Methods of Sending Photographs Details 
of the Cooley System Never Before Published An Efficient and Very 
Fast Transmitter Whose Applications are Many and Important 

By CHARLES C. HENRY 



I 



MAGINE, a hundred messengers deliver- 
ing photographic reproductions of busi- 
ness letters, photographs, printed matter, 
legal papers, social correspondence, and 
nnumerable forms of communication received 
from distant points by a single instrument. 
The instrument that will accomplish this 
is already known to many as a phototelegra- 
phic receiver. Few even of those who have 
followed the recent developments in photo- 
"elegraphy appreciate the huge commercial 

d economic importance it will have in the 
u j ar future. 

. Most of us read with interest the accounts 
of the transmitting of photographs across the 
Atlantic and admired the engineering achieve- 
ment of reproducing them with such fidelity 
here in America. In hundreds of magazines 
and papers, copies of the received pictures of 
President Coolidge, Secretary Hughes, the 
Prince of Wales, and others were prominently 
displayed. 

The whole world has heard about the trans- 
mission of the 1924 Republican Presidential 
Convention pictures by the American Tele- 
phone and Telegraph Company. The quality 



of the pictures received in New York from 
Cleveland compare favorably with the aver- 
age newspaper picture. 

The Chicago Tribune, the New York Daily 
News, and the Los Angeles Times have been 
tied together for several months with the Mar- 
vin Ferree system of phototelegraphy operat- 
ing over leased telegraph lines. Pictures 
are exchanged daily between these prominent 
newspapers and appear in their columns beside 
other news pictures. There is no noticeable 
difference in quality between the two. The 
trade name "Telepix" is attached to all of 
these telegraphed photos. 

Not long ago, C. Francis Jenkins, of Wash- 
ington, D. C., conducted radio phototrans- 
mission experiments between Anacostia, 
Maryland, and Medford Hillside, Massa- 
chusetts. His received pictures were badly 
mutilated by commercial radio telegraph 
traffic because of the particular wavelength 
used; but with better radio facilities at his com- 
mand, it is likely that his test pictures would 
have been quite successful. 

Edouard Belin is at present in New York en- 
gaged in the intensely interesting experiment 



20 



Radio Broadcast 



of attempting to re- 
ceive radio photo- 
grams from a Paris 
station. The St. 
Louis Post-Dispatch 
and the New York 
World have closely 
followed and sup- 
ported his work for 
many years. Using 
his system, these two 
newspapers trans- 
mitted pictures with 
great success last De- 
cember between St. 
Louis and New York 
City. 

Those engaged in 
this work of photo- 
telegraphy are racing 
with each other in 
their attempts to 
build up the first 
strong commercial 
foundation. It seems 
evident that the com- 
mercial field will be 
limited to one or two 
systems. It is quite 
possible that the 
ultimate system will 
be made up of 
contributions by the 
many scientists now engaged in the work. 

Millions of dollars have been spent for the 
development of phototelegraphy by those 
who appreciate its adaptability to handling 
communications of all kinds, whether it be 
photographs, drawings, script, or printed 



Thirty-Seven Seconds for a 
Picture 

The Cooley system, described in Mr. Henry's 
article, is capable of transmitting a five-by- 
seven-inch half-tone photograph or a line 
drawing over a perfect wire line in thirty- 
seven seconds. There are other methods in 
present use which send photographs by radio 
and by wire, but the time consumed is from 
four to fifteen minutes. Speeding up the 
transmission involves very great technical 
problems. Notable among these are the 
systems of the Radio Corporation, the 
American Telephone and Telegraph Com- 
pany, Marvin Ferree, Edouard Belin, and 
C. Francis Jenkins. RADIO BROADCAST is 
proud to present this story of Mr. Cooley's 
achievements, particularly because much of 
the development work was done in its own 
Laboratory. 

Every sign points toward the early per- 
fection of a commercially practicable system 
of phototelegraphy whose aid and influence 
in industry will be incalculable. RADIO 
BROADCAST believes the technical attain- 
ments of Mr. Cooley's system are of the great- 
est importance. Every reader who is inter- 
ested in general scientific progress and all 
those engaged in developing radio and wire 
communication will read of what has been done 
with the deepest interest. THE EDITOR 



matter. The speed at 
which typewritten 
messages may be 
transmitted over such 
a system is so great 
that one set of ap- 
paratus could handle 
all the messages go- 
ing between New 
York and Boston, 
which are now being 
tV a n s m i 1 1 e d over 
thirteen lines of au- 
tomatic printing tele- 
graph. The adapta- 
tion of phototelegra- 
phy to transoceanic 
radio communication 
will not only speed 
up the service but 
will tend greatly to re- 
duce the unfortunate 
effect that static now 
has. In the present 
system, letters form- 
ing the words are 
coded into dots and 
dashes and sent very 
rapidly. A bad crash 
of static will com- 
pletely destroy one or 
more words. Such 
a crash of static 

would only mar portions of letters from 
different words if the message were trans- 
mitted by phototelegraphy. To meet the 
keen competition of the cables, transoceanic 
radio companies must adapt some system 
that will insure reliability and at the same 




MOUNT RAINIER, IN WASHINGTON 

Transmitted by the Cooley system. Much of the recent development work on this system which was started 
in Cambridge, Massachusetts, in 1922, was done in the Laboratory of RADIO BROADCAST at Garden City 



A New Method of Transmitting Pictures by Wire or Radio 21 



time increase the capacities of their present 
stations. 

HOW PICTURES SOUND 

IF YOU should ever listen to radio signals 
that are serving to transmit photographs, 
you will hear a buzz of constant pitch but of 
varying intensity. The variations in in- 
tensity seem to repeat every second, or 
probably oftener, but each repetition will be 
slightly different from the previous buzz. 
Each impulse, that goes to make up the buzz, 
represents the light coming from a tiny area 
on the picture being transmitted. Every one 
knows that newspaper prints are made up of 
thousands of tiny dots. In light places on the 
pictures, these dots are very small. The 
dark portions are made up of dots so large 
they form together to make a solid black mass. 
When transmitting any photograph, a dot is 
sent with each electrical impulse, but these 
impulses occur so rapidly that they appear 
as a buzz when one hears them on the radio. 
Rows of dots are sent in rapid succession; this 
explains the repetition of the signal intensities 
at short intervals. It is not necessary to split 
the photograph up into tiny dots before trans- 
mitting, for this is automatically done by the 



electrical apparatus in the photograph trans- 
mitter. 

At the receiving station, the electrical im- 
pulses are transferred on a suitable paper back 
into dots and these dots are arranged exactly 
as they are on the original picture. To do 
this, both transmitting and receiving appara- 
tus must operate at exactly the same speed, 
that is to say, they must be synchronized. 
The technical problems involved in syn- 
chronizing have been some of the most impor- 
tant of the many difficult ones in developing 
the transmitting apparatus. 

A picture that is to be transmitted across 
the Atlantic by the Radio Corporation of 
America's system, or from one city to another 
over the Bell System lines, is first printed on a 
transparent film. This process is rather 
simple and does not require much time. 
Nevertheless, such a procedure would involve 
undesirable complications for constant and 
regular commercial service. Both the Tele- 
pix and Belin systems call for especial types 
of negatives peculiar to the transmitting 
methods employed. The making of such neg- 
atives requires a little more time than do the 
prints used on the Radio Corporation and 
American Telephone and Telegraph Company 




RADIO BROADCAST Photograph 
THE RADIO BROADCAST LABORATORY 

Showing the antenna and counterpoise system. Two masts eighty-five feet high support the two cage 

antennas. The longer antenna has a spread of 154 feet. The laboratory where Mr. Cooley did much of 

the development work on his photograph transmission system is located in the white cabin between the 

two masts. The buildings of Doubleday, Page & Company are in the background 



22 



Radio Broadcast 




BEFORE AND AFTER 

The original and a radio transmitted version of a photograph sent during the early experiments of the 
Cooley-Hainsworth system. The picture on the right was sent with fifty dots to the inch. Average news- 
paper halftones have sixty-five dots to the inch (this magazine's halftones have 1 10 dots to the inch) 



HON;R.B<HOWELL, OCTC8ER 1,1324-. 

UASHIKGTOH.D.C. 

OEAR SENATOR HOWELL:- MAY I CALL YO'JR ATTENTION TO A RE* 

VETHO'D OF cc^miicATios, THE RADIO PHOTO LETTER. IT RE- 
TAIKS THE AUTHr<nC CHARACTER OF AN AUTOGRAPH LETTER *HIU 
DELIVERING IT AT T8 SPEED OF RADIO. IT IS THE BEGINNING OF 
THE PRACTICAL APPLICATION OF *Y TEW. YSARS DEVELOPMENT OF A 
frAJMO SERVICE TO 7KE HYE, WHERE HERETOFORE. RAO 10. HAS BEEN 
DEVELOPED ONLY AS A SERVICE TO THE EA-?. ISN'T IT ABOUT 
TIKE "THE GOVSiWsOT BEGAN COtJSIQEHIHG A MORE RAPID COMM- 
5UCAT13N SERVICE TO BUSINESS? PHOTO COP l3 OF LETTERS ARE 
IN COURT. PHOTO COPi$ OF BUSINESS LETTERS J)E-v 
ev SADIC" CAT THE SPEED OF LIGHT) WOULD BE JUST- AS 

HTSC A!*0 BINDING WHfL.C SPEEDING UP CQ.V.V-ERCE EMORVOUSL Y 
ftiE L!K A?< ARJJY, C* GO FORWARD NO FASTER THAN ITS 
OF COaMUK'ICATIO^. A 0r? RAPID MEA^S OF INTERCOURSE 
S A Stsr TOOL FOR .SPEEDING UP BUSINESS. 

L VfEAtTH. 




A REAL RADIO LETTER 

Sent by the inventor of the system, C. Francis Jenkins, from Anacostia, 
Maryland, to Washington by radio last October. The Jenkins system 
has some points in common with the development of Mr. Cooley, but 
in essence, the Cooley system operates along other and entirely new lines. 
The radio photoletter may in a few years be an accepted part of our 
industrial svstem 



systems. A good com- 
mercial system of photo- 
telegraphy should be able 
to transmit, without 
further preparation, any 
photograph or message 
printed on ordinary pho- 
tograph paper. 

THE MECHANICS OF PHOTO- 
GRAPH SENDING 

SOME systems transmit 
the signals in dots and 
dashes instead of dots of 
intensity corresponding to 
the portion of the picture 
being transmitted. The 
dashes represent dark 
places in the pictures and 
the dots make up the 
light areas. This system 
is readily adapted to oper- 
ation on telegraph circuits 
or radio telegraph sta- 
tions. The cost of these 



A New Method of Transmitting Pictures by Wire or Radio 23 




CHARLES EVANS HUGHES 

Former Secretary of State, whose photograph was 
sent across the Atlantic by the Ranger-Radio 
Corporation of America " photoradiogram " system. 
The Ranger method, while used in this instance on 
a high power, long wavelength radio circuit, can be 
used on a wire line equally well 



communication channels is much lower than 
the ones required for the dot system as used 
by the American Telephone and Telegraph 
Company, Jenkins, Belin, and others. The 
Radio Corporation sent pictures across the 
Atlantic in twenty minutes by the dot-dash 
method. An hour or more is required to 
transmit a Telepix picture over a telegraph 
wire, but these pictures are larger and contain 
more detail than those handled by the Radio 
Corporation. The American Telephone and 
Telegraph Company have transmitted pictures 
of considerable detail in four or five minutes, 
but special wires were required. The cost 
of the communication channels used is an 
important factor that will determine the 
commercial value of any system. In some 
cases the high cost may be offset by the great 
capacity of the apparatus operating over the 
channel. 

When a system of phototelegraphy goes 
into commercial use, there will probably be 
separate rates for printed matter and photo- 



graphs. This is because the adjustments of 
the apparatus can remain fixed when handling 
black and white subjects while the transmit- 
ting of a photograph would require special 
attention so that the tones and shades 
ma^v be properly reproduced at the receiving 
station. A picture having little contrast and 
printed on sepia paper would require adjust- 
ments of the apparatus entirely different from 
one having contrast and printed on a glossy 
paper. 

THE STORY OF THE COOLEY SYSTEM 

E Cooley system, which has never been 
made public, incorporates more contribu- 
tions to the art than does that of any other in- 
ventor. This development is an outgrowth of 




VERITABLE RADIO WRITING 

A sample of writing of Doctor Hainsworth, one of 
the inventors of the Cooley-Hainsworth phototele- 
graph transmitting system. This was sent ex- 
perimentally in Cambridge in 1922 



Radio Broadcast 



work begun by Dr. William R. Hainsworth 
at the Massachusetts Institute of Technology, 
Cambridge, Massachusetts, in November, 
1921. From that time until March, 1923, the 
investigation centered on the use of methods 
paralleling very closely those made public by 
the American Telepho.ne and Telegraph Com- 
pany last summer. Austin G. Coolev, then 
a student at the Massachusetts Institute of 
Technology, joined Dr. Hainsworth in the fall 
of 1922 for the purpose of assisting in the ap- 
plication of radio to the equipment which was 
being operated satisfactorily in the laboratory. 
Having become convinced that this system 
was too unreliable, that it was definitely 
limited in speed, and that it was encumbered 



with so many obstacles in the way of its future 
acceptance as anything but an elaborate 
laboratory toy, in the spring of 1923 they 
decided to abandon their ideas and to start 
out along entirely different lines of research. 

C. E. Tucker, a well known authority on 
electrical communication; Prof. F. S. Dellen- 
baugh, a prominent electrical engineer; Dr. F. 
G. Keys, director of the Physical Chemistry 
Department at the Institute; Captain Clayton 
and Sergeant Truax, both of the United States 
Army Signal Corps, were a few of the members 
of the faculty of the Massachusetts Institute 
of Technology who took an active interest in 
the Cooley-Hainsworth development work 
and furnished valuable assistance in securing 




RECEIVING APPARATUS OF THE RANGER SYSTEM 

Used by the Radio Corporation of America. The picture is printed on the small revolving drum in the 
foreground which is driven by the motor directly behind it. Exact synchronism between the motor of the 
transmitting and receiving apparatus is an essential of all photographic sending systems. The first public 
demonstration of this system took place during the week of December i, 1924, between New York and 

London 



A New Method of Transmitting Pictures by Wire or Radio 25 




A TELEPIX PHOTOGRAPH 

Which was sent between New York and Chicago. The photograph was retouched after it was received. 
A comparison between this and the original below shows that considerable detail was lost in the transmit- 
ting process. A picture of this type is one of the most difficult to transmit 



the necessary apparatus and instruments. 
Dr. Jacob Kunz of the University of Illinois 
had contributed materially to the work by 



placing at their disposal his newly developed 
photoelectric cell. 

Many of the radio fans in the vicinity of 




AN ORIGINAL PHOTOGRAPH 
The telegraph version is shown above 



26 



Radio Broadcast 



Boston will recall hearing mysterious buzzes 
accompanied by clicks occurring at intervals of 
a little more than a second apart on a 200 
meter radio wave during the month of Decem- 
ber, 1922. Many inquiries were answered by 
explaining that "special tests on radio control 
were being conducted." Probably no one had 
the slightest conception that pictures were 
being sent over the air. It was from the ex- 
perimental radio station IXM, located at the 
Institute, that the pictures were transmitted. 
They Were received in Dr. Hainsworth's 
laboratory, not far distant. The quality of 
the received pictures was poor, but the work 
must be given considerable credit, for it was 
probably the first time that the synchronizing 
of the receiver with the transmitter was ac- 
complished by radio. 

The development work on the phototele- 
graphic system was conducted in Dr. Hains- 
worth's laboratory and radio station IXM 
where Mr. Cooley spent most of his time. In 
the summer of 1923, the first tests on the new 
system designed by Mr. Cooley were made in 
this radio "shack." It is seldom that appara- 
tus of new and unusual design meets its 
builder's expectations. Mr. Cooley was pre- 
pared to be disappointed. But on the con- 
trary, unusual and encouraging results were 
obtained. 

With the aid of a colleague, Mr. R. A. 
Cunningham, Mr. Cooley rushed along the 
construction work on a complete set of appara- 
tus to be used for demonstration purposes. 
Dr. Hainsworth left Boston during the summer 
of 1923 to take up some other work in Seattle. 
Since that time he has not been able to take 
an active part in the development of the 
phototelegraphy system for which he is respon- 
sible. 

AT THE RADIO BROADCAST LABORATORY 

WHEN Arthur H. Lynch, editor of this 
magazine, was asked to assist in obtain- 
ing laboratory space for the development 
of the Cooley phototelegraphic work, he 
was quick to realize its possibilities. Without 
the slightest hesitation he freely offered 
the facilities of the RADIO BROADCAST Lab- 
oratory for the test of Cooley's ideas. 
Accordingly, night and day, and with this 
precious equipment constantly under the eyes 
of watchmen, Cooley pursued his tests of 
a high speed phototransmission device for 
reproducing at distant points photographs 
having all the shades necessary to make up a 
perfect picture. 

It was not until after the International 



Radio Broadcast Tests in December, 1924, 
that the various units of the new Cooley 
phototelegraphic system had been properly 
coordinated and it was possible to send pic- 
tures of satisfactory quality in the RADIO 
BROADCAST Laboratory. Arrangements were 
made to loop the picture signals through two 
local telephone exchanges and to return them 
to the Laboratory, where both transmission 
and reception might be watched by the opera- 
tors. The transmitter was connected to a 
telegraph line which terminated at the RADIO 
BROADCAST office. At this point, the signals 
were acoustically transferred to a telephone 
which was connected to the private branch 
exchange of Doubleday, Page & Company. 
This private branch exchange was in turn 
connected to the Garden City telephone ex- 
change, where the usual telephone connections 
were set up for the wire which serves the 
Laboratory telephone. 

SUCCESS ON THE FIRST TEST 

IN THIRTY minutes ten pictures were 
transmitted. The apparatus was readily 
synchronized within ten seconds before the 
reception of each picture began. The pictures 
transmitted were taken from magazines and 
rotogravure sections of newspapers. In the 
receiving apparatus, the pictures were printed 
out on an inexpensive photographic paper 
that required developing and fixing before 
the image could be seen. The thirty minutes 
mentioned included the time required for this 
work. The quality of the received pictures 
was fair, in spite of a defective device in the 
transmitter. This device was the photo- 
electric cell, a necessary part of the equipment. 
Air had leaked into it and caused its action to 
be sluggish. A new one is now being built by 
Dr. Kunz, especially designed to meet the high 
speed requirements in this system of photo- 
telegraphy. 

The limitations of the Cooley system are 
unknown. It is probable that a commercial 
type model, which can handle four hundred 
messages an hour, will be constructed within 
the next year. Compare this with the present 
machine-printing telegraph, which averages 
about fifty messages an hour. 

Using the Cooley design, the transmitter or 
receiver is neither bulky nor expensive to con- 
struct. In a commercial embodiment planned 
for an early date, a portable transmitter will 
be built for the use of newspaper photogra- 
phers. It will be necessary only to connect the 
machine to the electric light socket, get the 
newspaper office by telephone, and place 



A New Method of Transmitting Pictures by Wire or Radio 27 



the negative, still wet from the developing 
solution (if utmost speed is desired) in the ma- 
chine, and, in the course of a minute or two, 
transmit it to the photographer's headquar- 
ters. And, wonderful though it may seem, the 
photographer may send it to be received as 
either a negative or a positive. He may also 
send a print or even a clipping from a magazine 
or newspaper and have the replica in the hands 
of the editor within a few minutes after com- 
pleting his telephone connection. Since this 
work may be done acoustically, there is no 
need of any electrical connection between the 
photo-transmitter and the telephone. 

ONE PICTURE EVERY HALF MINUTE 

MR. COOLEY has not lost sight of the 
fact that 1200 impulses per second is 
about the maximum number that can be trans- 
mitted over a commercial telephone line. 
This limits the speed of transmission to about 
seventeen square inches per minute if the pic- 
ture is to be printed out with sixty-five dots 
per inch, this being standard for newspaper 
prints. The speed might be increased through 
the use of high quality transmission lines such 
as are used for carrying programs from a studio 



to a broadcast station. In such lines the 
circuits are so arranged that frequencies up to 
4000 cycles per second are passed. At the 4000 
impulse rate, only thirty-seven seconds would 
be required to send a five-by-seven-inch picture. 

Before this copy of RADIO BROADCAST reaches 
the reader, it is confidentially expected that 
the necessary alterations in the present model 
will be made, so that the most detailed photo- 
graph with all its half-tone shadings can be 
transmitted over any telephone or radio circuit 
that is capable of transmitting intelligible 
speech. There is every hope for the early de- 
tailed announcement of this phototelegraphic 
system that is fundamentally new and novel in 
its transmission and receiving methods. 

The quality of the photographs transmit- 
ted by this system can be made especially 
good for magazine use. By increasing the 
speed of transmission, photographs can be sent 
at a greater speed, for use in newspapers. I n its 
final form, the apparatus will be extremely sim- 
ple, relatively inexpensive, and equally adapt- 
able for line or radio transmission. 

In connection with this work, a very im- 
portant new use of the vacuum tube has been 
discovered and a very plausible theory has 




THE ORIGINAL AND THE TELEGRAPHED PHOTOGRAPH 

Sent from New York to Chicago by the "Telepix" system now in use by the Chicago Tribune and the 
New York Daily News. The cut on the right is a print of the wired picture after it had been slightly re- 
touched. At present, wired photography is decidedly expensive and too slow for general commercial use 



28 



Radio Broadcast 



been formulated for its operation. Still an- 
other use of the vacuum tube has been de- 
veloped to an extent which shows excellent 




promise. It is now thought that it can be 
included in the design of a new and novel re- 
ceiving circuit which will be a great improve- 
ment in the sensitivity as compared to present- 
day receivers. Many patents are now pending 
for the various inventions which have been 
made in connection with the Cooley system. 
As rapidly as the patent work permits, 
RADIO BROADCAST will disclose the technical 
developments that are made as the work 
progresses. 

There has been much discussion in recent 
years about the theories of the German scien- 
tist Einstein and his theory of the relativity 
of time and space. In a very definite and 
striking way, the radio transmission of photo- 
graphs illustrates the contentions of that 
famous scientist, although certainly not in the 
way he intended. 

This new art has reached the stage where 
commercial telephone, telegraph, and radio 
companies must recognize it as an ally or pre- 
pare to meet its competition. The constant 
barrier of distance is again about to be dealt a 
blow as deadly as that delivered by the general 
utilization of the locomotive, automobile, 
airplane, the telegraph, and radio. Since 
time is the only important measure of geo- 
graphical space, phototelegraphy bids fair 
appreciably to shrink the magnitude of our 
world. 



CALVIN COOL1DGE 

President of the United States. This photograph 

was also sent across the Atlantic by the Ranger 

system. The dots and lines which go to make the 

picture can be clearly seen. 



COMPLETE instructions on how to build the Roberts four-tube Knockout re- 
^ ceiver so that it can be fitted into any phonograph cabinet will appear in an 
early number of RADIO BROADCAST. It is now possible to buy manufactured 
sets which can be used in a phonograph cabinet, but thus far, no information has 
yet appeared which is of any help to the home builder. The mechanical details 
of the receiver are especially well worked out and the panel can be used with 
any type of cabinet phonograph now on the market. 



How the Government Is Regulat- 
ing Radio Broadcasting 

The "Interest of the Listener" Is the Final Test of Regulation 
The Present Situation and Future Possibilities An Inter- 
view with Judge Davis of the Department of Commerce 



BY R. S. McBRIDE 



INCREASING service to the listener," is 
the only proper basis for radio regulation 
and development in the opinion of Her- 
bert Hoover, Secretary of Commerce. 
But it is a long way from this generalization 
to the practical working out of a Government 
policy. So RADIO BROADCAST has undertaken 
to study the depart- 
mental policy as to the 
control of broadcast- 
ing to see just what 
this statement really 
means. For this pur- 
pose, an interview 
was secured with 
Judge Stephen B. 
Davis, Solicitor of the 
Department of Com- 
merce, with results 
that are most grati- 
fying from the point 
of view of the listener. 
There is no doubt 
that the radio audi- 
ence is assured of 
every protection and 
aid which the skilled 
agents of the Govern- 
ment can offer and 
that fair and helpful 
service will be given 
to any broadcasting 
development that has 
real merit. 

GARDENING FOR JACK 
OF THE BEAN STALK 

E can well im- 

agine the troubles which a gardener 
would have had caring for the yard of Jack 
of bean-stalk fame. But such a gardener 
would have had no more trouble in pruning 
the bean stalk to shapely form than does the 
Department of Commerce in directing the 



The Wavelength's the Thing 

Everyone who knows the pleasant pressure 
of head phones or who is often attentive to a 
loud speaker has discovered that the ether 
paths are becoming more crowded every day. 
The average radio listener if there is such a 
person has probably wondered how the 
Government is dealing with the serious prob- 
lem of distributing the broadcast wave- 
lengths, which, when one considers the num- 
ber of applicants for the comparatively few 
available, are few enough. There has been a 
deal of excited speculation on what would 
happen if a number of so-called super-power 
stations were licensed speculation, it may 
be said, with only an indifferent knowledge 
of the facts. Mr. McBride has gone to head- 
quarters for his information and we think he 
has presented very well the attitude of the 
Department of Commerce. The Depart- 
ment is charged with administering the Radio 
Act under the very difficult changing condi- 
tions of radio. That radio progress has not 
been greatly hindered by hasty and ill- 
considered legislation is due to the many good 
and capable friends of radio who have used 
their influence honestly and well in Wash- 
ington. THE EDITOR 



growth of the radio broadcasting business. In 
this, as in the fairy tale, not even the sky is 
the limit, so it seemsj 

Four years ago or August, 1921, to be 
exact the first broadcasting was begun. 
To-day the Department lists nearly 600 broad- 
casting stations in operation or under con- 
struction. These 
must be guided and 
safeguarded if the 
real interest of the 
industry, which 
means the wishes of 
the general public of 
listeners, is to be 
adequately protected. 
And with ether space 
so much at a prem- 
ium to-day, the task 
is not an easy one. 

In view of the con- 
tinued rapid growth 
of broadcasting, many 
have foreseen a con- 
stantly increasing 
confusion in the air, 
which would be help- 
ful to no one and 
harmful to all. An- 
ticipating this situ- 
ation the Department 
was asked, "How 
much worse must 
things get before they 
can begin to improve 
again?" Or put- 
ting it another way, 
"How much more 

broadcasting interference must the public 
tolerate before it will rise up and demand rigid 
regulation and complete elimination of the 
interfering stations?" 

These questions were addressed to Judge 
Davis, who is really acting as first officer of 



Radio Broadcast 



the good ship Radio. The answer which he 
makes is most encouraging. He says, "Con- 
ditions will not be allowed to get any worse. 
They are far too bad already." Pressed fur- 
ther on this matter, Judge Davis stated that 
there are no more wavelengths available for 
broadcasting in the Class B wavelength area. 
Practically, this is an announcement to all 
newcomers in the broadcasting field that they 
will not be permitted to crowd in and add 
confusion between 280 and 550 meters. And 
to the broadcast listeners, as to all other well 
wishers of radio, this is the most welcome news 
of many months past. 

FIXED CONDITIONS TO-DAY CHANGE TO-MORROW 

BUT in stating this conclusion, Judge 
Davis repeatedly emphasized that no 
plan of the Department can be regarded as 
permanently fixed. Radio itself is changing; 
the Department's plans must keep pace or 
become a handicap. It is clearly the purpose 
of the Department to prevent any such un- 
fortunate result. For to-day, however, it is 
safe to conclude that the Department intends 
to protect the listener's interest by limiting the 
number of stations which can work within the 
so-called Class B range. To-morrow some 
new scheme may develop which will permit 
granting of more Class B licenses on these 
wavelengths, but radio science to-day does not 
apparently hold forth this possibility. 

Already in this Class B range, the average 
broadcast listener has a choice of several pro- 
grams at ordinary broadcasting hours. But 
the Department is not content with this, for 
it seems to be well demonstrated that with a 
gradual advance in power at the stations in 
different parts of the country, the number of 
unquestionably good programs from which the 
great body of radio listeners may choose can 
be increased up to eight or ten. If so, many 
different stations can be made regularly 
available to each of us. There will then 
be ample opportunity for choice between 
grand opera, jazz, oratory, and educational 
productions. The Department is working 
toward this goal, cautiously, to be sure, 
but with every confidence that it is entirely 
practicable. 

SAFE-GUARDING SMALL STATIONS 

CLASS B stations with power of from 500 
to 2000 watts now afford the most relia- 
ble broadcasting service over a considerable 
area. But the Department still regards the 
small local stations of great importance to 
the communities that they serve. Secretary 



Hoover, commenting on this situation at the 
recent radio conference, said: 

1 know the importance of these smaller stations 
to the communities they serve. 1 know that there 
are millions of crystal sets and small tube sets whose 
owners are practically compelled to-day to rely 
upon the stations at their doors and are getting good 
service from them. These are the people I have in 
mind and the ones 1 primarily want to serve, for the 
owner of the multi-tube set, reaching out for an in- 
definite number of miles, is pretty well able to look 
out for himself. 1 want to see the little fellow get 
something more than he has now. 

From this statement it is evident that any 
plan for improving the service from the power- 
ful Class B group is not going to involve serious 
hazards for local use of low-power stations that 
fit properly into the general scheme of things. 

The Department, Judge Davis emphasizes, 
still regards the small set, even the crystal set, 
as the most important unit for consideration 
in planning broadcast regulations. 

THE SUPER-POWER BUG-A-BOO 

THE recent suggestion of Mr. David Sar- 
noff that one or two very powerful stations 
using perhaps 50,000 watts should be erected 
to serve the entire country aroused a storm of 
protest. Much of the objection came from 
misunderstanding. Some came from propa- 
ganda spread abroad by small-station broad- 
casters who feared the results of such a 
development. The Department was quick to 
answer these objections with the announce- 
ment that no alarming or radical changes are 
being contemplated. 

Thus far, Judge Davis explains, only two 
stations have advanced as far as 2000 watts 
and only eight or ten are using as much as 
1 500 watts. This advance has been made in 
steps of 500 watts and each forward step is 
closely watched by the Department. 

The object of these advances is two-fold: 
First, an increase in the dependability of radio, 
from the listener's point of view, over the 
ordinary range of regular reception. Second, 
an extension of the effective range so that the 
rural districts of the country will be adequately 
served and afforded some choice of program 
wherever that is possible. The first of these 
advantages means regular loud speaker service 
from stations that now are simply passable 
contributors to the family enjoyment when 
head phones are used. The second advantage 
means widening of the possible field of service 
without creation of any new stations, new 
interference, or new expenses. 

The useful range of a broadcasting station, 



How the Government is Regulating Radio Broadcasting 



the Department emphasizes, is the area within 
which signal strength is sufficiently greater 
than static or other interference that the pro- 
gram is regularly audible at all times dur- 
ing broadcasting periods. Broadcast stations 
with inadequate power are about as useful as 
an ordinary telephone beside a pneumatic 
riveter. We know the message desired is 
coming through the instrument, but it does 
us no good. Until we find out how to quiet 



In the early days the Department decided 
that a spacing between stations of ten kilo- 
cycles was as close as could properly be used 
without interference. In other words, they 
permitted each station to take a seat ten 
kilocycles wide. Now all the seats are taken 
and each man must hold his overcoat on his 
lap and put his hat under his own seat. Nat- 
urally it seems a bit more crowded; but, as 
the Department officials clearly explained, it 




HERBERT HOOVER AND JUDGE STEPHEN B. DAVIS 

Captains of the good ship Radio. As Secretary of Commerce, Mr. Hoover for the last four years has had to 
face some very difficult administrative problems, for radio communication has greatly altered during that 
time. Broadcasting was merely a commercial experiment in 1921. Compare the radio situation when 
Mr. Hoover took office, with conditions on the fourth of March, 1925, when the whole country was "hooked 
up" by wire and radio and enabled to hear the inaugural ceremonies in Washington. Judge Davis, as the 
solicitor for the Department, has been in direct touch with radio affairs and it is known that his opinions are 

very similar to those of Mr. Hoover's 



the riveter of static we have no choice but to 
increase the power of the station so that we 
can hear it despite this interference. 

IS BROADCAST CROWDING ONLY APPARENT? 

IF WE go to the movies in the early afternoon 
there is usually plenty of room so that we 
can put our hat and overcoat in a vacant seat 
beside us and sit with comfort any place in 
the theater that. we may choose. So it was in 
radio broadcasting a few years ago. All of the 
newcomers found plenty of room. They 
were given wavelengths that allowed all the 
freedom for careless operation that the crudi- 
ties of early apparatus made inevitable. But 
to-day the broadcast territory is as badly 
crowded as the movies when the town's favor- 
ite star is showing in her newest film. 



is simply that all the assignments possible are 
now made, not that there is any closer assign- 
ment authorized to-day than heretofore. 

The Department undertook a series of ex- 
periments during the middle of the winter to 
see whether a closer spacing was not feasible. 
In other words, they tried to make each radio 
seat a few inches narrower. On attempting 
a seven-kilocycle spacing in this experiment, 
came the answer very clearly. The De- 
partment admitted that the answer was very 
definitely "No!" 

Secretary Hoover has announced this find- 
ing in unmistakable language. He says, "The 
recent experiment of the Department in at- 
tempting to increase the number of wave- 
lengths by decreasing the difference to seven 
kilocycles proved unsuccessful with the present 



Radio Broadcast 



development of instruments." And, further 
on in a recent official statement, the Secretary 
stated that "it is absolutely necessary to main- 
tain a wide kilocycle separation between 
stations so close together (geographically). 
Otherwise they will destroy each other." And 
as the Department well recognizes, they will 
destroy the listener's patience and interest 
even more promptly. 

THE SURVIVAL OF THE FITTEST 

EVOLUTIONISTS explain that the ad- 
vance from animal to man occurred by 
the survival and development of the fittest 
form of life. In radio, a similar evolution to 
the high-class station which all can anticipate 
for the future is now in progress. When one 
station makes great improvements, the neigh- 
boring stations have three choices: 




DAVID SARNOFF 

Vice-president and general manager of the Radio 
Corporation of America. At the third annual radio 
conference in Washington which met at the call of 
Secretary of Commerce Hoover in October, 1924, 
Mr. Sarnoff suggested that the way to solve some of 
the broadcasting problems would be to license 
several very high-powered stations of the order of 
fifty kilowatts which, located in various parts of the 
nation, would give dependable broadcast service 
over a large area. A high-powered broadcast sta- 
tion has recently been erected by the British Broad- 
casting Company in England 



1. They may keep up by making similar im- 
provement. 

2. They may confess inferiority by continuing on 
the old superseded basis. 

3. They may go out of business. 

The history of radio indicates that alterna- 
tives i and 3 are about the only possible ones. 
Judge Davis made this point very clear by a 
large radio map which hangs on his office wall. 
On that map blue pins show the Class B 
stations, green pins the Class A, and black 
pins the stations that have been, but are no 
more. At almost every point where blue pins 
appear they are surrounded by the black 
markers of discontinued stations, stations 
which could not stand the pace and there- 
fore quit rather than confess permanent 
inferiority. 

The Department is wondering whether this 
is not a necessary and logical course to be fol- 
lowed. That station which is most progressive 
and gives the best service, judged always from 
the standpoint of the listener, will succeed. 
The neighboring stations which cannot do 'so 
well are not long in learning that their effort 
and expenditure is producing no advantageous 
result. It is well from all points of view, even 
their own, that they should go out of business; 
fortunately they do. 

CONCENTRATION WITHOUT MONOPOLY 

THE Class B stations, which now afford the 
widest and most dependable class of serv- 
ice, offer the most serious problem in inter- 
ference. Any DX fan in the center of the 
country can safely boast that his set will reach 
from Orono, Maine, to Los Angeles, and from 
Winnipeg to Cuba, but his boast is true only 
when he speaks of Class B stations, for those 
of Class A rarely have sufficient power to be 
heard more than occasionally beyond a hun- 
dred miles. 

In the Class B range there are built or build- 
ing more than 100 stations, with only forty- 
seven wavelengths to be distributed among 
them. So now, on the average, there is less 
than one wavelength for each two stations, 
which means that many Class B stations must 
divide their time of operation. This division 
of time has led to much difficulty; but the 
Department, for the present at least, is allow- 
ing the problem to solve itself. 

UNCLE SAM: HOTEL CLERK 

THE Department in radio takes much the 
same attitude as the room clerk at a 
popular hotel. As evening approaches all of 
the rooms are engaged, yet there are numerous 



How the Government is Regulating Radio Broadcasting 



33 




DR. J. H. DELLINGER AND D. B. CARSON 

Dr. Bellinger .is. head of the radio laboratory of the Bureau of Standards, which, being a division of the 
Department.^ Commerce, works closely with the Radio Service. D. B. Carson is Commissioner of Naviga- 
tion and is the general supervisory head of the Radio Service 



demands for accommodations still to be met. 
In the radio Class B hotel, it is sun-down and 
all of the wavelengths are assigned. What 
does Uncle Sam, the' radio room clerk, do? 
Just what the hotel clerk would do under the 
same circumstances. 

The newcomer arrives and wishes accommo- 
dations. If he has a friend who will share 
with him his room, or Class B wavelength, 
the clerk welcomes him and makes this room 
assignment. He is glad to have each double 
bed filled with two paying guests. If a third 
friend arrives and the first two are willing to 
have a cot placed in the room, all are happy 
and are all accommodated. But if the late- 
comer does not find such a friend to accommo- 
date him, obviously the clerk will not turn out 
one of his regular patrons to make room for the 
newcomer, nor will he insist that the earlier 
arrival share his bed, or wavelength. 

Uncle Sam, in planning wavelength assign- 
ments in the Class B wavelength range, takes 
the same stand. As the Secretary of Com- 
merce puts it, "The Department cannot give 
what it has not got." And it is perfectly clear 
that there are no Class B wavelengths left. 
Hence one can properly read between the lines 
of the Department's recent statement that 
there will be no further assignment of Class B 
wavelengths for the present or the near future. 
Nor will the Department willingly destroy the 
value of present wavelength assignments by 



demanding that they be shared with late- 
comers. 

"S. R. O." AT THE BOX OFFICE 

I ET us go back again to the theater for 
L comparison with the radio station. The 
early-comers, or those who bought tickets in 
advance, fill all the seats, yet there is a long 
line at the box office despite the sign "Standing 
Room Only." Uncle Sam, with no radio 
seats in the Class B orchestra, has hung out 
his "S. R. O." sign, too. But he will, in fact 
under the law he must, grant licenses and 
assign wavelengths. He does this by a ticket 
of admission which entitles the new broad- 
caster to work only in the Class A range, 205 
to 280 meters. In this range he is not com- 
fortably seated as a member of the radio 
broadcasting party. He finds himself stand- 
ing behind the back seats, jostled by other 
late-comers, and seeing the performance at 
great disadvantage. But he is simply paying 
the penalty as a late-comer. 

If some of the present Class B stations dis- 
continue service or cease to give service ade- 
quate from the public point of view, their li- 
censes, which are renewable every 90 days, 
will doubtless not be renewed for comfortable 
third-row aisle seats. In fact, Uncle Sam, 
just as the theater management, reserves the 
right to withdraw the admission ticket at any 
time. Hence a disorderly station, like a dis- 



-34 



Radio Broadcast 



orderly spectator, will promptly find himself 
outside. As one leaves, another may be 
seated. The place he gets depends upon the 
appropriateness of location, service proposed, 
and wavelength thus made available. 

THE CINCINNATI " ROW " 

RECENTLY, a controversy over division 
of broadcasting time in Cincinnati was 
not promptly settled by the local Class B sta- 
tions, two of which for several nights broadcast 
simultaneously on the same wavelength. The 
Department officials were asked in this and 
in one other similar case, "What are you going 
to do about it?" The answer was very simple, 
"Nothing." 

If two stations insits on killing themselves 
and each other, the Department is perfectly 
willing that they should do so but it will not 
allow this situation to interfere with public 
service. Two such disorderly patrons of the 
radio hotel will be permitted to settle their 



controversy outside. The wavelength which 
they should have agreed to share peaceably 
will very promptly be given to someone else 
who will use it in the public interest. 

Only one or two such examples will be 
ample to demonstrate to broadcasters that 
the public interest must be served. On no 
other basis can the radio broadcaster exist. 
On no other basis will he be permitted to re- 
tain his Class B license. 

POLICING IS NOT CENSORSHIP 

THE Department properly is insisting that 
each station maintain a certain technical 
standard of service and that it stay properly 
on its own wavelength. But the Depart- 
ment is equally emphatic that this is policing, 
not censorship. 

Judge Davis explains that neither he nor 
any one else in the Department is willing to 
assume that they know enough to determine 
on behalf of the public what may and what 




WHERE AMERICAN RADIO ACTIVITIES ARE CONTROLLED 

The Department of Commerce building in Washington. Here, in the Bureau of Navigation, Radio Service 
offices, the administrative lines run to the entire nation. The Department controls every amateur operator 
with a transmitting station and every commercial ship and shore station, as well as the very host of broad- 
casters. The radio inspection staff and the appropriation supplied them has never been large enough so that 
the inspection duties could be adequately done 



How the Government is Regulating Radio Broadcasting 



35 



may not be broadcast. Whether such a 
station provides jazz or education, whether it 
runs from six o'clock to midnight, or from 
midnight to noon, is not defined or regulated 
in any way. The public is the judge, and the 
public makes its wishes known in no uncertain 
manner to the broadcast station which does 
or does not serve its needs or whims. 

But providing all this power over the 
stations for the listener is not an easy mat- 
ter, and at times the Department does not 
get undivided encouragement and support 
from the public. One difficulty which has 
been raised by the effort to protect the Class 
B wavelengths against undue crowding is the 
vigorous protest of some listeners that they 
cannot separate accurately all of the stations 
in the Class A group, the band from 205 to 
280 meters. Naturally they cannot; and as 
crowding in that band becomes worse, the 
difficulty will be greater. But this crowding 
is in the public interest. It means that 
nine tenths of the useful wavelength area is 
reasonably safeguarded by suitable spacing 
between wavelengths and only one tenth is 
crowded. As the listener understands the 
great advantage of this, the Department 
hopes that it may gain even greater support 
for this idea. Certainly from the point of 



view of the public, nine-tenths of the radio 
loaf is better than none. 



A LMOST since 1912 when the Department of 
* Commerce was charged with the enforce- 
ment of the radio laws, and certainly since the 
advent of broadcasting, they have struggled 
along as best they could, making Herculean 
efforts to accomplish their tasks with the piti- 
fully small staff and Congressional appropria- 
tion granted them. The radio affairs of the 
country are supervised from nine district 
offices. If each radio inspector had an 
equal territory, that would give each one 
five and one third states to look after. And 
in some district offices, an inspector and 
one or two assistants are expected to do all 
the work. 

The recommendations of the radio con- 
ference, called in October, 1924, by Secretary of 
Commerce Hoover, were the consensus of the 
"best minds" of radio who were gathered 
there. It is generally agreed that the reason 
the changes suggested were not put in force 
was because the Department was so crippled 
in available funds and in personnel that any 
additional undertakings on their part were 
absolutely out of the question. THE EDITOR. 



T T E WAS a distance fiend, 
JL JL A leather of anything near. 

Though WOOF had a singer of opera fame, 
And wow a soprano of national name, 
He passed them both up for a Kansas quartet 
A thousand miles off and hence " harder to get." 

New York was too easy to hear. 
He was a distance fiend. 



He was a distance fiend, 

His radio ruling his life. 
When he and his family went to the play, 
He'd take them to Yonkers instead of Broadway. 
The show being over, he'd blow to a bite 
In far Staten Island, that very same night. 

God pities his daughter and wife, 
He was a distance fiend. 



He was a distance fiend. 

Alas, but he died one day. 
Saint Peter obligingly asked would he tell 
His choice of a residence Heaven or Hell? 
He replied, with a show of consistency fine: 
"Good sir, you have hit on a hobby of mine. 

Which place is the farthest away ?" 
He was a distance fiend. 

A. H. FOLWELL, in The New Yorker 




RADIO IN A VIRGINIA CAVE 

Endless Caverns at Newmarket, Virginia. Experiments with radio reception have been tried in many un- 
usual locations from coal mines to bank vaults, but it is doubtful if any radio equipment has been located in 

more picturesque surroundings 



THE MARCH OF RADIO 



B- 




Past President, Institute of Radio Engineers 



What Does the New Allocation of Broadcast Wavelengths 

Mean? 



JUST why the Department of Commerce 
reallocated many broadcast wavelengths 
is not evident. "The Department of 
Commerce has been engaged for some 
time in an attempt to divide the ether 
more efficiently than has been the case hither- 
to," was the announcement from Washington. 
Here are some examples of the new assign- 
ments: WEAF 491.5 meters, instead of 492, 
WGBS 315.6 instead of 316, wjy 405.2 instead 



of 405, WHN 361.2 instead of 360, etc. These 
changes are so insignificant that just what is 
gained is not at all evident. Certainly no new 
channels have been created by such diminutive 
shifts from former wavelengths. The changes 
are so small that unless very careful observa- 
tion was made before and after the change, 
the average listener would not realize that any 
change had been made. If for example, 
WJY tuned at 30 on a condenser dial before, 



The March of Radio 



37 



it will now tune at 30.03, but such a shift is 
much less than the width of one of the division 
marks on the dial. Most of the changes in the 
other well known stations are of equal insigni- 
ficance insofar as the average listener is con- 
cerned. 

The First Presidential Radio Inaugural 

GREATER and greater become the 
radio audiences which are invited to 
attend the country's important events. 
When President Coolidge took the oath of 
office on March 4, the whole country was en- 
abled to listen-in, and we must add, his 
speeches generally make very good listening. 
At least 21 stations participated in the broad- 
casting network, extending from Boston to 
San Francisco, and from St. Paul to Atlanta. 
This was the Telephone Company group and 
in addition, WRC, wjz, and WGY of the Radio 
Corporation were tied in by their own wires. 

It must give President Coolidge increased 
courage (if such were necessary) to reaffirm his 
stand for safeguarding the country's funds 
this idea of realizing that he can talk directly 
to probably 15,000,000 of his countrymen. 

We hope that soon Congress will be 
forced to broadcast its activities. Verbose 
senators may have their activities some- 
what rationalized and sobered if they 
realize that secret chamber procedure is no 
longer available to them. Not very many 



of them would care to vote in the affirmative 
to increase their own salaries immediately 
after the president had outlined his economy 
program that is, they wouldn't care to if 
they knew that a few million of their constitu- 
ents were listening carefully to their words. 

What Membership in the Institute of 
Radio Engineers Means 

FREQUENTLY we get inquiries about 
the status of some radio writer who 
signs himself "radio engineer" or 
some such title, or declares his status by giving 
membership in this or that society. It is 
perhaps pertinent to explain the significance 
of membership in the Institute of Radio Engi- 
neers. Insofar as we know, this is the onJl-y 
bona fide association of radio engineers in 
existence. 

In its membership of about 2500, three 
grades are recognized, and the ranking of a 
member in one or the other of these grades 
gives a very trustworthy estimate of the man's 
standing in the radio profession. 

Anyone of mature age who is actively in- 
terested in radio may become an Associate 
member of the Institute. The applicant has 
certain formalities to go through, such as 
filling out a regular membership blank giving 
his training, business, references, " etc., but 
no difficult conditions are imposed to hinder 
him from becoming an associate memiber. 




THE FIRST RADIO INAUGURATION 

President Calvin Coolidge, taking the oath of office from Chief Justice William Howard Taft, of the United 
States Supreme Court March 4, 1925, was the first time in American history that an ex-^presidenit ad- 
ministered the oath of office to an incoming president. The twenty-four stations which broadcast the 
ceremonies practically linked up the entire nation 



Radio Broadcast 




ENGAGING A HOTEL ROOM AND RADIO 

Is now possible at the Drake Hotel in Chicago, the Roosevelt in 
New York, and the Benjamin Franklin in Philadelphia. A portable 
set is installed in the room of the guest ordering it. Having an in- 
dividual receiver allows the guest to select his own radio entertain- 
ment. In some large apartment houses, hotels, and hospitals a 
central receiver has been installed and the output is then wired to the 
various rooms. The disadvantage is that but one program can be 
heard at a time and little or no selection is offered the guest 



apartment houses in New York, 
the management of the Roosevelt 
has decided that the guests could 
be better served by putting ac- 
tual radio sets in the rooms. To 
start the experiment, a dozen 
portable receivers with self- 
contained loop antennas have 
been purchased and are at the 
call of any guest. Presumably 
the management will see that 
the sets are maintained in good 
condition, and the guest has 
merely to ask for radio service, 
and a receiving set will be dis- 
patched to his room at once and 
he may tune-in on any station 
he desires. 

Broadcast Licenses Should 

Be Granted Only on 

Petition 



The rank as Associate I. R. E. does not carry 
with it any certification by the Institute that the 
member is or is not a capable radio engineer. 

To become a member of the Institute 
(Member, I. R. E.) a man must submit to the 
Board of Direction a record of his radio 
achievements. This record is carefully scru- 
tinized by men who know the radio field well. 
Membership is given only if the man's record 
shows him to be a capable engineer of sufficient 
ability to carry out any ordinary radio project. 
Possibly one quarter of the total membership 
of the Institute have the rank of member and 
in this group will be found practically all those 
engineers who are responsible for modern 
radio development. 

The Institute has for its highest grade of 
membership that of Fellow. This rank is be- 
stowed only upon those few engineers who 
have proved themselves leaders in the radio 
field. Probably less than one twentieth of 
the total membership has been given this 
highest rank. 

Radio a la Carte 

THE Hotel Roosevelt, New York among 
others has installed a novel radio service. 
Instead of putting a receiving station 
on the roof and installing wires to the guest's 
room as has been done in some of the larger 



A i CHURCHES, hotels, Elks, 
Klansmen.'and apparently 
everyone else, scramble for 
broadcasting licenses, and get 
them, the question must occur 
to any one with common sense, where is it all 
leading to and why should the practice be 
kept up? What policy controls the Depart- 
ment of Commerce in issuing licenses? Or 
has it no policy? Is the real situation the 
same as the apparent one that any one can 
get a broadcasting license who applies for it? 

Apparently feeling that he owed the public 
some comment on the rapidly congesting con- 
dition of the radio channels, whirh is accumu- 
lating under his direct supervision, Mr. Hoover 
recently issued a long statement on the radio 
situation parts of which we quote: 

There are at present 563 broadcasting stations in 
operation, or under construction. The most diffi- 
cult problem in radio regulation and development 
is the distribution of wavelengths in such a way as 
to prevent interference between stations. There 
are in all 86 different wavelengths available, if we 
keep the stations 10 kilocycles apart and stagger the 
assignment of wavelengths geographically so as 
to prevent overlap in the area of effective reception. 

The recent experiment of the Department in at- 
tempting to increase the number of channels by de- 
creasing the difference to 7 kilocycles proved un- 
successful with the present development of radio 
receiving apparatus. 

All through the lengthy document we 
searched to see if Mr. Hoover did not expect 
some time to lessen his license-issuing activi- 
ties. There is no mention of it. It looks as 



The March of Radio* 



39 



though the Secretary thought he had no dis- 
cretionary power in withholding permission 
from the new stations, or else that he greatly 
feared to use it, but that conclusion scarcely 
seems justified in view of the personality of 
the present Secretary. 

According to one of the writers in the New 
York Times: 

There is difficulty in seeing just what excuse there 
is for granting the broadcasting privilege to one 
applicant and denying it to others equally reputable. 
Nevertheless a justification for drawing the line 
somewhere on mere numbers of grantees must be 
found if radio is to progress toward the realization 
of its possibilities, or if it even is to retain those 
which it now demonstrates. 

Some time soon Mr. Hoover will have to say 
"No, I cannot see that the interests of the 
radio listener will be served by granting you a 
license, so I must decline to issue one to your 
anticipated station." It scorns as though 
someone is missing the real idea of radio's 
possible progress. The issuance of a license 
should not depend upon either precedent, 
favor, standing of the applicant, fear of em- 
barrassment, or any other item of this nature. 
As many of our correspondents continually 
point out, the question Mr. Hoover has to 
ask himself is, Do 
the listeners want 
this proposed sta- 
tion? If they don't 
want the station 
then the license 
should not be 
granted. 

We venture to 
suggest that a 
new applicant be 
obliged to accom- 
pany his request 
for a license by a 
petition, signed by 
at least 100,000 
people who live 
within, say 50 miles 
of the site of the 
proposed station. 
The number of re- 
quired petitioners 
should depend 
upon the locality 
around Chicago 
and New York it 
might well be 
1,000,000, and in 
sparsely settled 
country, possibly 



50,000 or less. This procedure would decide 
the question just as it should be decided in 
the interest of the radio listener. 

Will the British Receiver License 
System Fail? 

WE HAVE mentioned onceor twice that 
if this government should ever decide 
to take over radio broadcasting and 
should attempt to maintain the service by 
collecting revenue from the listeners in the 
form of a tax or license, it would require a 
tremendous force of collectors with hundreds 
of thousands of warrants, to make the collec- 
tions good. We think that the broadcast 
listener does not want to be licensed, and if the 
good American public does not want to pay a 
license fee, it probably won't. The nation has 
been told to stop drinking intoxicating liquor 
for some years now, but hasn't yet agreed to 
submit to a ban on what is still regarded by 
many as a "legitimate," even though unconsti- 
tutional, privilege. 

There are several countries where license 
fees from the listeners are depended upon for 
maintaining broadcast service, among them, 
England. We can safely say that the Eng- 




ROY A. WEAGANT 

Chief Engineer of the De Forest Radio Company, at work on a receiver circuit in bis 

laboratory 



Radio Broadcast 



lishman is a more law-abiding citizen than 
we are. The Post Office authorities, who 
have the task of supervising British radio, 
estimate, says a news dispatch, that there are 
2,500,000 pirates, who have listening sets but 
who have not paid the government fee. A 
bill is urged to permit drastic punishment for 
these ether robbers. Twelve months' im- 
prisonment or $500 fine has been suggested. 
Even should such a measure be enacted, 
trouble would still be encountered because 
before entering a man's house a warrant is re- 
quired, and the promiscuous issuance of search 
warrants would certainly arouse a tremendous 
antagonism in a land where every man's cottage 
is supposedly still regarded as his castle. 

If there really are 2,500,000 radio pirates in 
England, it doesn't augur well for the license 
system of control. If these reports are accur- 
ate, it looks as if the license system in England 
is doomed to fail in the very near future. 

Radio Quality Will Count 

yi S WE glance through the radio adver- 

f-\ tisements each month, it is only too 

plain . that many radio firms, like 

Kipling's ships, "pass in the night." Many a 

man who knew nothing whatever of the radio 



game, was persuaded by some overenthusiastic 
adviser that "mints of money" were to be 
gleaned from the radio public. All one had 
to do was to get something which sounded like 
radio and then spend lots of money on adver- 
tising. After that it was to be nothing but a 
matter of counting profits. These inexper- 
ienced radio adventurers are the ones who 
come and go but few of them last to enjoy 
the confidence of the radio public. 

As these bargain-apparatus firms start up 
with apparently a tremendous price slash over 
the older and more conservative firms dealing 
in the same line of goods, it must frequently 
seem to these manufacturers that their sales 
are due for a slump. But they don't slump 
and if the quality is maintained high, they 
won't. New as radio is, people already realize 
that the apparatus with a name behind it is 
probably worth more than the nameless waifs 
with which the irresponsible -store has its 
shelves loaded. A reliable firm name means 
much in the paint, steel, or tool business. 
.Conservative radio firms, whether they manu- 
facture panels, binding posts, condensers, or 
what not, will soon start to reap the benefit 
of their reputation. It probably won't be 
very long before the radio public learns to buy 
"by the name" rather than "by the price." 




THE WRITING ON THE WALL 

During the presentation of a radio play in an English broadcasting studio. The typewritten pages of the 

manuscript were projected on a screen on the studio wall where all could see it. The microphone, English 

style, is enclosed in the rectangular box in the center 



The March of Radio 




Vacuum Tubes 

in Another 

Legal Tangle 

JUST before the 
De Forest au- 
dion patent 
expired, the attor- 
neys for his com- 
pany brought 
about an action 
which had a start- 
ling effect upon 
the Radio Corpo- 
ration subsidiaries. 
In the United 
States District 
Court at Wilming- 
ton, Delaware, 
Judge Hugh M. 
. Morris, granted an 
injunction which 
stopped the Radio 
Corporation's sale 
of tubes manufac- 
tured by the West- 
inghouse Lamp 
Works. The case 
involved nothing 
of direct interest 
to the radio lis- 
tener. It seemed merely to be a legal squab- 
ble. 

When one stops to think of it, the legal pro- 
fession seems to be the most inbred union 
in existence. You have to be a lawyer to 
make a law, and you have to be a lawyer to 
prove that someone else is breaking a law. 
Furthermore, one can't become a lawyer un- 
less the rest of the union wants him, because 
the lawyers write the entrance examination 
for the union. One set of lawyers draws up 
a legal document to permit a lamp company 
to manufacture vacuum tubes and another 
lawyer hails them into court to show that 
their law was bad. It appears that the De 
Forest agreement which would permit the 
Wcstinghouse Electric and Manufacturing 
Company to manufacture tubes would not 
permit the Westinghouse Lamps Works to 
do so, even though it is acknowledged by all 
that the Lamp Company is simply that part 
of the Westinghouse Company which had the 
facilities for making tubes: The Manufac- 
turing Company is equipped for making 
motors and all kinds of electrical machinery, 
but not for turning out delicate lamps and 
vacuum tubes, and so naturally turned its 



ABOARD THE S.S. "GEORGE WASHINGTON" 

Captain Cunningham has a broadcast receiver which he uses in the time he can 

spare from his nautical duties. Captain Cunningham was navigator of the U. S. A. 

T. Leviathan during the War. From left to right, Captain Cunningham, W. J. 

Roche, and T. H. Rossbottom 



tube activities over to the lamp division. 
Judge Morris ruled that even though the 
parent company had the right to manufacture 
tubes, the Lamp Company had no sQch right 
and all the tubes it had wrongfully manufac- 
tured must be confiscated and held. 

So the lawyers go, one getting a company 
into trouble, so that another can get it out. 
It looks as though in this case the attorneys 
for the De Forest Company have been a little 
bit shrewder than those of the Radio Corpor- 
ation. 

Radio Dispute in Cincinnati 

THE ever increasing number of broad- 
casting licenses issued by the Depart- 
ment of Commerce is practically certain 
to bring trouble in a short time, in ever increas- 
ing amounts. Some method of equitably 
limiting the number of stations must be found 
by the Department. It is their job and they 
might just as well tackle it now. 

A strange instance of the Department's in- 
activity took place in Cincinnati. Two 
stations in that city had been granted licenses 
to operate on the same wavelength. After 
much squabbling as to the proper division of 



Radio Broadcast 



time, they finally did operate on the same 
wavelength at the same time! It was re- 
ported from Washington that the Department 
of Commerce had been repeatedly asked to 
step in and settle this impossible situation but 
had declined on the ground that to set such 
a precedent would get the Department hope- 
lessly enmeshed in a maze of disagreements 
between stations. 

One might well ask the Department how it 
did expect such disputes to be settled. It is a 
strange idea of privilege and duty which con- 
sents to the issuance of broadcasting licenses 
to any who want them and then when trouble 
comes to the listening public as a result of the 
excessive number of stations, to turn one's 
back and let someone else settle the trouble 
trouble directly due to the Department's 
freedom with its licenses. Who, we may 
well ask, does Mr. Hoover think will step in 
to straighten out such troubles between the 
various stations, if his department thinks the 
task too onerous? 

Making Radio Transmission Surer 

IN A recent talk before the American Insti- 
tute of ElectricarEngineers,jMr. Alexander- 
son, chief consulting engineer of the 
Radio Corporation, gave a general description 
of their network of channels which is being 




LAYING A ROGERS UNDERGROUND ANTENNA 
At Hyattsville, Maryland. Dr. J. Harris Rogers is nearest the camera. 
The Rogers system has been developing experimentally for some time and 
has been watched by officials of the War and Navy Departments 



rapidly extended over the earth. After out- 
lining general troubles and difficulties which 
an engineering audience could well appreciate, 
the speaker went more into detail to show how 
the Radio Corporation was continually work- 
ing to increase the certainty of communication 
over their radio links. He spoke of the re- 
markable wave antennas used at Riverhead, 
over which signals from all the stations in 
Europe are received. Although static has 
not been annihilated by the R. C. A. engineers, 
this reception scheme of theirs ensures com- 
munication unless there is a severe local thun- 
derstorm. To obviate the possibility of such 
a storm interferingwith transatlantic channels, 
another receiving antenna has been fitted up 
in Maine, so that either can now be used, de- 
pending upon where the atmospheric disturb- 
ance is least. 

He spoke of new features in short wave 
transmission, a so-called high-angle beam. 
If one could rely upon his rather scanty de- 
scription, it appears that he thinks it may be 
possible to send short wave energy from one 
place to another by some kind of beam system 
which is directed high up in the air. to come 
down at a desired spot by reflecting from the 
earth's upper conducting atmosphere. This 
story reads more like a poet's dream than 
like an engineer's narrative, so don't give it too 
much credence as yet. 

It may be possible to send 
beams of energy high up in 
to the sky and so around the 
Heaviside layer, but it is 
more likely that such an 
etfect will be found in Eng- 
land than here. America has 
done practically nothing 
with directed beam trans- 
mission, but Marconi and 
Round seem to be progress- 
ing continually along just 
these lines. 

If directed beams sent 
high into the air actually 
get much farther than those 
sent along the earth's sur- 
face they would probably 
have found out and reported 
it to us long ago. 

The Day of Good Music 

'ERV recently a most 
welcome announce- 
ment was made by 
Mr. John A. Holman, 
broadcasting manager of 



V 



The March of Radio 



43 




station WEAK. The 
public's demand 
for jazz has greatly 
decreased, he as- 
serts, as evidenced 
by the letters re- 
ceived from the 
station's listeners. 
Of the many thou- 
sands of listeners 
who now write in, 
by far the most 
want good music, 
he says; and 
thanks be, say we, 
that the managers 
are waking up to 
the fact that the 
whining, croaking, 
saxophone with its 
associated agony- 
producing pieces 
of barbarism, are 
due for the dis- 
icard, as far as 
the radio listener 
is concerned. 

Mr. Holman 

evidently thinks there has been a change 
of appreciation on the part of the listen- 
ers, but we doubt this very much. The let- 
ters no doubt indicate such to be the fact, 
but it seems more likely that the admirer 
of jazz would write enthusiastic letters to 
the broadcaster more often than a lover of 
Chopin and Mozart. The appreciator of jazz 
is the one who makes the most noise, just as 
a dozen wild American- Irish would make 
enough noise against such a speaker as Mr. 
Lloyd George to drown out the approbation 
of the remaining 2000 in the audience. This 
has probably been the case with the radio 
audience those who wanted good music are 
the quiet type who suffered much and long 
before remonstrating against the finally un- 
bearable monotonies of much of the modern 
jazz. 

What the Radio Corporation Did in 
1924 

SEVERAL points in the annual report of 
President Harbord of the Radio Cor- 
poration for the year 1924 demand 
comment. We think it is only fair to give the 
Radio Corporation credit for being the first 
to inaugurate broadcast concerts by well- 
known phonograph recording artists. The 
idea, which was later taken up by the American 



CHARTING THE DEPTH OF THE PACIFIC OCEAN 

With the sonic depth finder, a new application of well-known radio principles. The 
apparatus projects a vibration which follows through the water to the ocean bed; it 
is then reflected back. The elapsed time is measured from which the depth of 
water can be calculated. Lieut. Clore of the U. S. S. Pioneer is shown in the radio 
cabin of his vessel operating the depth finder 



Telephone and Telegraph Company with 
much success, originated in an agreement be- 
tween the Radio Corporation and the Bruns- 
wick-Balke-Collender Company. This inno- 
vation in broadcasting programs was an 
inspiration, and it is a pleasure to record our 
appreciation of its inception. 

In speaking of the value of the radio busi- 
ness, General Harbord made the interesting 
statement that for every dollar spent on 
musical instruments of all kinds, phonographs, 
pianos, and organs, seventy-five cents was 
spent on radio. Radio business was about 
three-quarters that of the entire jewelry 
business of the United States. 

In transoceanic traffic, radio carried be- 
tween twenty and thirty per cent, of European 
traffic, and fifty per cent, of the trans-pacific 
messages. Apparently the proportion of radio 
to cable messages is not changing very rapidly, 
as it is our recollection that about the same 
proportion existed during the previous year. 

Radio Raises Cable Earnings 

INSTEAD of taking business away from the 
transoceanic cables, the development of 
radio appears actually to have put money 
into the coffers of the cable companies, accord- 
ing to a statement of Clarence H. Mackay. 
Mr. Mackay says that the Commercial Cable 



44 



Radio Broadcast 




E. F. W. ALEXANDERSON 

Schenectady; Chief Consulting Engineer, 

Radio Corporation of America 
" There is a large and growing group of amateurs 
who pursue radio for the love of the art. The art 
to them is not the performance in the studio hut 
the technical art of radio itself. Radio has en- 
joyed a greater following of amateurs than any 
other branch of engineering, and it is the thought 
of these amateurs that moulds the future. They 
are one step closer to reality than the imaginative 
writers, like Kipling and Jules Verne, who give 
us glimpses of the future long before they can be 
realised. The amateur likes to anticipate what 
advances in the art may reasonably be expected 
within the next decade" 



Company had handled more business over its 
cables in 1924 than during any previous year 
of the company's existence. 

The changing economic situation in Europe 
was reflected in a growing demand for cable 
service, and as for radio's encroachment on the 
cable's territory, Mr. Mackay says "on the 
contrary, the radio has actually stimulated the 
use of electrical communication between the 
continents, and of the new business so created, 
the cables are really getting more than their 
proportionate share." 

Mr. Sarnoff As An Optimist 

SEVERAL times during the last decade 
the press has chronicled that someone 
had laid low Demon Static and that 
hereafter, by the application of some heaven- 
born device, radio was to be freed of trouble- 
some atmospheric disturbances. Too well 
now, we know that these were all illusions. 
But now Mr. Sarnoff, General Manager of 



the R. C. A., strikes an entirely different note 
when mentioning static. At a recent dinner 
he ventures the opinion that static, after all, 
is not an unmixed evil. 

I often wonder, whether the same minds saw the 
limitations of radio telephony because of the lack 
of secrecy, and now see a limitation of radio because 
of static, might not be disappointed to wake up some 
morning in the future to find that the static, which 
is all-pervading, represents a great and free gift of 
nature to man, who may yet learn to harness that 
energy, get it from the air, and make it do a great 
work for man. 

Not seeing through the same rosy-hued 
glasses as does the speaker on this occasion, 
we venture that the man who gets static out 
of the air, no matter what he does with it 
after he removed it from the radio realm, will 
already have done a great work for man. 

Incidentally, Franklin with his kite did 
show us exactly how to do this thing quite 
some vears ago, didn't he? 



Interesting Things 
Said 



Interestingly 



P\R WILLIS R. WHITNEY (Schenectady; di- 
*-^ rector of research for the General Electric 
Company): "We are building a $150,000 laboratory 
to be devoted to research in the field of directional 
radio and short wavelengths. Our experimenters 
have obtained results on wavelengths on less than 
fifty meters. We can't yet explain why such waves 
travel as far as they do, with relatively weak im- 
pulses behind them, or why they should have passed, 
unaffected, through the belt of darkness produced 
by the eclipse, while the longer wavelengths were 
either accelerated or deflected. . . . 

We can look for the transmission of power by radio 
if we are satisfied to use 99 per cent, of our power in 
transmitting the other one per cent. It is a matter 
of cost. So long as it is cheaper to send power over 
wires, there is no incentive to send it over the air. 
The ordinary radio transmitter sends power through 
the air, though in relatively small quantities It 
may be more economical to send power through the 
air for operating a powerhouse switch than to send 
a man to do it." 

'THE REV. FATHER JOHN HANDLY (So- 
* ciety of the Paulist Fathers. New York): "The 
thing that impressed me along the lines of my daily 
work in collecting money for the new Paulist League 
broadcasting station was the fact that our Divine 
Lord was describing a scene very familiar to me in 
the parable of the Sower and the Seed, because I was 
reared on a stony briar-choked farm down in Ten- 
nessee. . . . There are many who are doubtful 
about the value of radio as a. means of teaching relt- 



The March of Radio 



45 



gion. I want to call their attention to this point 
that our Lord thought it worth while to broadcast 
the Word of God in spite of the fact that some of 
the seed fell by the wayside. ... He thought 
it worth while because he hoped some would fall on 
good ground and bring forth fruit." 

\A7ILLIAM A. FISCHER (Boston; in a recent 
" * paper read before the Music Teachers' Na- 
tional Association in St. Louis): "Radio listeners in 
this country are tax free and have been trained to 
expect a startling variety of entertainment for 
nothing, while broadcasters have been, and still are, 
placing their dependence on performers and speakers 
who give their services without pay in their eager- 
ness for publicity. Thus a vicious circle has been 
started. Until artists worth paying for are regularly 
engaged, radio concerts, with exceptions, will con- 
tinue to be merely a source of advertising to imma- 
ture performers who, instead of helping the public to 
enjoy good music, often cast opprobrium on it by 
their inadequate and inarticulate performances." 

D OBERT L. COX (New York; second vice- 
*^- president, Metropolitan Life Insurance Com- 
pany, speaking of the Company's plans for broad- 
casting setting-up exercises through WEAF, WJAR, 
and WEEI): "While -radio itself is no experiment, 
the use of it for teaching health is still in the develop- 
mental stage. We are going to give the radio audi- 
ence what they want in this respect, but we don't 
propose stopping with the letters. We have other 
means of finding out what people want. . . . 
Through our agents, we shall be able to make a 
house-to-house canvass and learn what the radio 
fans think, not only of our health messages and 
exercises, but of radio programs in general." 

D OBERT H. RANGER (New York; engineer, 
^ Radio Corporation of America; in charge of 
development work of the Radio Corporation system 
of transmission of photographs by radio): "For 
eighty years a thousand or more investigators and 
certainly millions of dollars have been concerned in 
the attempt to transmit pictures successfully at a 
distance. Economics enters into the problem as 
much as mechanical and electrical design. In the 
photoradiograms transmitted across the Atlantic 
in December, we narrowed them down to a kind of 
sketchy, shorthand form, because of the economic 
factors of time, power, and cost, all of which are 
highly important in picture transmission. . . . 
The response accorded photoradiograms, which was 
far greater than those of us who have been concen- 
trating on prosaic long-distance wireless telegraph 
communication ever expected, has greatly encour- 
aged us in our efforts to refine and improve the 
transmitted picture." 

D UDOLPH H. WURLITZER (New York; man- 
F^- ufacturer of musical instruments): "Our 
company believes that radio will develop the musical 
taste of the people of the United States more 
rapidly than if radio had not existed. We regard 
our sales, totalling $14,782,576 during a nine- 




MARTIN P. RICE 



Schenectady; Director of Broadcasting, 

General Electric Company 
" The Department of Commerce is now embar- 
rassed by the number of broadcasting stations 
desired in comparison to the number of wave- 
lengths available. A reallotmenl of wavelengths 
is now in progress in the hope of improving con- 
ditions for the radio listener. It would be highly 
desirable to provide an exclusive wavelength for 
each station operating with sufficient power to 
reach across the continent and having programs 
of national interest. Such a plan would increase 
materially the reliability of long distance broad- 
cast reception and the increased range would 
stimulate the large stations to strive for the best 
in programs. Progress along these lines would 
not restrict the development of the strictly local 
stations designed to reflect the community life of 
their own districts. Such stations, operating 
on another band of wavelengths, have their own 
function and they may, on occasion, be tied into 
the general or national group by means of wire 
lines or radio rebroadcasting" 



months' period when radio was mounting in popu- 
larity, as compared with $13,653,809 during the 
same period in 1923, as significant. It is estimated 
that more than thirty million people in this country 
play some musical instrument. When such a large 
population of players have their natural human in- 
terest in music stimulated by the radio programs, 
an increased demand for musical instruments is not 
at all surprising." 

"THIS ADVERTISEMENT is a "tabloid His- 
* tory of American Civilization; a capsule cri- 
tique of the Higher Learner in these U. S/A.; it ap- 
peared in the Shreveport Journal," comments F.P.A. 
in the New York World. The advertisement: 
ONE SET HARVARD CLASSICS, 51 Books, 
new, for Radio Receiving Set. Box 634, 
Journal. 



How to Design Radio Coils 

A Simple Non-Mathematical Method- Which 
Can Be Applied by Any Radio Constructor 



BY HOMER S. DAVIS 



ONE of the most frequent problems 
confronting the amateur radio 
builder is the design of the induc- 
tance coils of a new receiver. 
Often the size of tubing or kind of wire speci- 
fied by the designer is unobtainable, or one 
may prefer to re-design a coil to conform to the 
principles of low-loss design. "Cut and try" 
methods are crude at best, and if the amateur 
has some means of easily computing the in- 
ductance of a coil, he can save both time and 
expense by its use. 

The solenoid, or single-layer winding, is a 
common form of coil, and it is rather generally 
agreed to be the most efficient for a given value 
of inductance. But although the simplest 
to design, the formula for a solenoid is rather 
difficult to use unless one is quite familiar with 
mathematics. Fortunately, there are several 
methods of representing formulas graphically, 
and of these, the alignment chart is probably 
the easiest to use, and therefore offers the best 
solution to our diffi- 
culties. A pencil and 
a ruler are all that are 
required to use these 
charts. 

A discussion of the 
manner in which they 
were worked out is 
given below for the 
benefit of any who 
may care to follow it 
through, although it 
is not in any way 
essential to the use 
of the charts. The 
reader may skip en- 
tirely over this discus- 
sion if he so desires. 

The formula for 
the inductance of a 
single -layer solenoid 



crohenries, d the diameter in inches, n the 
number of turns per inch, I the length of the 
solenoid in inches, and K the shape factor. 
The latter depends upon the ratio of the diam- 
eter to the length, and its value may be ob- 
tained from tables in the Bureau of Standards 
Bulletin No. 74 and elsewhere. Thus it is 
not especially difficult to solve for the induc- 
tance of a coil when d, n, and 1 are known. 
But the factor K causes no end of trouble when 
we try to use the formula in the reverse di- 
rection, solving for 1, since K is then an un- 
known also. Cut and try methods must be 
resorted to. We can express K in a for- 
mula in terms of d and 1, but the relationship 
is not simple. However, in most cases, the 

value of the ratio - lies between and 2, and 

between these limits we may express K as 
approximately: K=o6?4 /d\ -* 



(r) 



where L represents 
the inductance in mi- 



A Coil Calculator 

Is what the chart which accompanies this 
article of Mr. Davis's, really is. Any number 
of constructors who tried to build a radio 
set from directions have been stopped short 
by their inability to secure a certain size 
coil and had no way of calculating its size, 
except by mathematics. And mathematics, 
to many of the radio constructing gentry, is 
not a desirable part of the picture. Many 
of the advanced radio calculations lead one 
directly into the calculus. Those who wish 
nothing more than a good rule-of-thumb will 
find the chart will allow them to build 
coils to the specifications of the various con- 
struction articles, will allow them to build a 
coil to attain a certain wavelength range with 
a condenser of given size, and by reversing 
the process, it is possible to find out what 
size condenser should be used with a given 
coil to attain a known wavelength. The 
chart and the wire table should be of great 
help to the builder of sets. THE EDITOR 



Substituting this in 
the first formula, we 
have: 

L = .oi69n- > d I - 7tt7 l 1 - 29:J 
and K has been eli- 
minated. It is now 
possible to solve for 
any one value when 
the three others are 
known. It is still a 
formidable looking 
equation, but it may 
be charted with ease. 
It is hardly necessary 
to explain here how 
the charts are con- 
structed, but suffice 
it to say that they 
are based upon the 
same theory as the 
slide rule, which was 
described in the "R.. 
B. Lab." department 
of the January 192^ 
number of RADIO 
BROADCAST. 



How to Design Radio Coils 



47 



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15 



Radio Broadcast 



The formula from which Chart i was con- 
structed is 



where X represents the wavelength in meters, 
L the inductance in microhenries, and C the 
capacity of the tuning condenser in micro- 
farads. 

Referring to Fig. i, it is seen that the two 
charts have been placed side by side, with the 
L-scale in common. As an example of the 
use of these charts, let us say that we wish our 
tuned circuit to reach a maximum wavelength 
of 550 meters, and that we plan to use a .0005 
mfd. variable condenser tubing three inches in 
diameter, and No. 18 d. c. c. wire. With a 
pencil and ruler we draw a line from .0005 
on the C-scale through 550 on the X-scale, 
until it intersects the L-scale, reading 170 
mh., as the required inductance of our coil. 
Another line is drawn from L= 170 to d = 3. 



Referring to the copper wire table, Fig. 2, we 
find that No. 18 d. c. c. wire can be wound \g.6 
turns to the inch, so we draw a third line 
from this value on the n-scale, through the 
intersection of the second line and the index 
line, until it intersects the I-scale. This 
shows us that the coil should be wound to 
a length of three inches, and the product of 
n and 1 gives 59 as the number of turns re- 
quired. 

The chart may be worked in the reverse 
direction in exactly the same manner, always 
making sure that the correct pairs of scales are 
connected together. 

The amateur builder will find many uses 
for these charts. In addition to their value 
in designing inductances for a new receiver, 
they may be used to redesign a coil for dif- 
ferent sizes of tubing, wire, or tuning con- 
denser than originally specified. 



KIND OF INSULATION 


B. & S. 


DCC 


sec 


DSC 


ssc 


ENAMEL 


ENA 
AND 


MEL 
AND 


GAUGE 




























sec 


SSC 


14 


13.7 


14.6 


14.7 


15.0 


15.2 


14.2 


14.7 


15 


15.0 


16.2 


16.4 


17.0 


17.0 


15.8 


16.5 


16 


16.7 


18.0 


18.2 


19.0 


18.7 


17.6 


18.4 


17 


18.5 


20.0 


20.0 


21.2 


21 A 


19.5 


20.5 


18 


19.6 


22.3 


22.3 


23.6 


24.0 


21.7 


22.9 


19 


22.5 


25.0 


25.2 


27.0 


27.2 


24.2 


25.8 


20 


24.5 


27.5 


27.5 


29.5 


30.1 


26.5 


28.4 


21 


27.5 


30.8 


30.8 


32.8 


33.6 


29.6 


31.5 


22 


30.0 


34.0 


34.0 


36.6 


37.7 


32.7 


35 


23 


32.7 


37.5 


37.5 


40.7 


42.3 


36.1 


39.0 


24 


35.5 


41.5 


41.5 


45.3 


47.2 


39.7 


43.1 


25 


38.5 


45.7 


45.7 


50.3 


52.9 


43.7 


47.9 


26 


41.8 


50.2 


50.2 


55.7 


59.0 


47.8 


52.8 


27 


45.0 


55.0 


55.0 


61.7 


65.8 


52.1 


58.1 


28 


48.5 


60.0 


60.0 


68.3 


73.9 


57.0 


64.4 


29 


52.0 


65.5 


65.5 


75.4 


82.2 


61.9 


70.6 


30 


55.5 


71.3 


71.3 


83.1 


92.3 


67.4 


77.9 


31 


60.0 


77.3 


77.3 


91.6 


103.0 


72.8 


85.3 


32 


62.7 


83.7 


83.7 


101.0 


116.0 


79.1 


93.9 


33 


66.3 


90.3 


90.3 


110.0 


130.0 


85.6 


103.0 


34 


70.0 


97.0 


97.0 


120.0 


145.0 


91.7 


112 


35 


73.4 


104.0 


104.0 


131.0 


164.0 


98.8 


123.0 


36 


77.0 


111.0 


111.0 


143.0 


182.0 


105.0 


133.0 


37 


80.3 


126.0 


126.0 


155.0 


206.0 


113.0 


146.0 


38 


83.5 


133.0 


133.0 


168.0 


235.0 


120.0 


157.0 


39 


89.7 


140.0 


140.0 


181.0 


261.0 


128 


172 





FIG. 2 
Wire turns per linear inch 




OVER THE TOP 



RADIO BROADCAST Photograph 



A layout view showing the actual scarcity of wiring. The 
angle of placement of the coils is clearly indicated 



How to Build a Two-Stage Radio 
Frequency Amplifier 



BY JOHN B. BRENNAN 



1~*HE amplifier described in this article incorporates some new and desirable ideas 
in construction. Leads have been reduced to the shortest possible length, 
the famous Roberts system of double-wound coils has been used for the neutral- 
ization of each stage, and the especially efficient diamond weave coils employed for 
the transformers. This unit is simply a radio-frequency amplifier which can be 
connected to any detector. A later article will describe a detector and audio- 
frequency amplifier which may be used with it. In these days of high power broad- 
cast stations, the selectivity gained by the use of radio frequency amplification is 
especially desirable. By completely neutralizing both stages of this amplifier, 
the full gain from each tube is secured. The simplicity of design and the ease of 
construction of this unit, in addition to its important feature of non-radiation, 
should appeal to every constructor. THE EDITOR 




EFORE dealing with the construction 
of a radio-frequency amplifier it is 
well to understand just what radio 
frequency energy is and how it may 
be amplified. 

The signal radiated by a broadcast station is 
composed of many electromagnetic vibrations 
or alternations. Due to many causes, such 
as the power of the transmitting station, 
absorption losses, location of the receiver, etc., 
these impulses which are collected by the 
receiving antenna may be too feeble to actuate 
the detector tube. When this is the case, 



little or no rectification in the detector tube 
takes place, making it impossible for the signal 
to be heard. To state the case simply, the 
detector tube performs the function of rectify- 
ing and making audible the very high or radio 
frequencies which cannot be sensed by the ear. 
This tube, so to speak, transforms or lowers the 
radio-frequency currents to an audible or 
audio-frequency current. 

The vacuum tube can function as an am- 
plifier (or repeater,) and it is possible to 
strengthen the amplitude of the very feeble 
received signal from the antenna, by means cf 



Radio Broadcast 



a radio-frequency amplifier, before it reaches 
ihe detector. 

Contrary to the general belief, the original 
signal potential is not passed along and ampli- 
fied in these successive stages of radio- 
frequency amplification. The action in these 
units is more on the order of a trigger releasing 
device. To understand this, the action of an 
amplifier must be observed. 

THE TRIGGER ACTION OF THE TUBE 

WHEN a signal is applied to the grid 
of an amplifying tube, the electronic 
emission from the filament is interrupted in its 
path to the plate because the grid acts as a 
shutter or trigger device. By means of a 
local source of potential (the B battery), the 
variation in signal frequency is faithfully 
reproduced in the plate circuit of the tube in 
the form of a varying, direct current potential 
many times greater in strength than the 
original signal applied to the grid of the tube. 

In other words, the vacuum tube has re- 
peated and amplified the incoming signal with- 
out changing any of its characteristics. 

We have so far traced the action in this 
circuit to the plate circuit of the first tube. 

A typical two-stage radio-frequency ampli- 
fier with detector and one-stage audio ampli- 
fier is shown in Fig. i . 

Now in this plate circuit is contained the 
primary coil Pa of the radio-frequency coup- 
ling unit. This unit, consisting of the primary 
and a secondary which is connected to the 
input of the next tube, performs the function 
of inductively coupling one tube circuit to 
the next so that the signal received by the 
antenna may be repeated at a greater ampli- 



Mu, OR AMPLIFICATION FACTOR 
OF TUBE 




-Incoming Signal 

(continuous wave* 

which is impressed 

on Grid of Tube 



FIG. 2 

How a tube amplifies, graphically shown. This only 

takes into consideration the amplification factor of 

the tube. Actually, the amplification is greater, due 

to the step-up value of the r. f. coupler unit 

tude in each successive stage. In this instance, 
the unit is a radio-frequency transformer. 
When the variation of current takes place 
in the first plate circuit, coinciding with the 
variation of frequency of the received signal, 
an electro-magnetic field is set up in and about 
the plate coil, the intensity of which varies 
with the variation of the plate energy. This 
varying magnetic field induces in the secon- 
dary of'the transformer, which is the grid coil 
of the next tube, a magnified voltage corre- 
sponding exactly to that to be found in the 
preceeding plate circuit. (The direction in 
which the current flows in the two coils is 



AUDIO 
AMPLIFIER 




no. i 

A typical radie-frequency amplifier circuit. Oscillation control is obtained by the potentiometer 



How to Build a Two-Stage Radio-Frequency Amplifier 



opposite, but, for our present study, that fact 
makes no difference.) 

Then, of course, the magnified signal is 
applied to the grid of this second tube and 
the entire tube action is repeated again, and 
so on for each successive stage. See Figs. 
2 and 3. 

The variable condensers 1-2-3 shunted 
across the various secondaries are employed 
to tune the circuits to the wavelength of the 
received signal. For this reason the unit ?2, 
82 and 2 in combination, is called a tuned 
radio-frequency transformer. We may sum 
up then by saying that in action, a radio- 
frequency amplifier will magnify the feeble 
antenna vibrations which ordinarily would 
not be strong enough to actuate the detector 
tube. 

While radio-frequency amplifiers do, to a 
certain degree, increase the volume of a re- 
ceiver, their main function is to amplify feeble 
radio energy which comes from great distances. 
This is the way in which a radio-frequency 
amplifier will increase the receiving range of a 
radio receiver. Such an amplifier will not, 
as a rule, increase the volume of signals which 
are already strong enough to be heard well. 

THE DESIGN OF AN AMPLIFIER 

""pO PASS the action of amplification from 
* one tube to another, called cascading, 
some coupling means, which was previously 
explained, must be employed. 

Several methods for coupling have been 
devised, such as untuned transformer-coupled, 
tuned impedance-coupled, and tuned trans- 
former coupled. The names indicate the 
method employed to induce energy from 
the plate circuit of one tube to the grid of the 
next. Amplifiers employing tuned radio- 



frequency transformers have been generally 
accepted as the most satisfactory and they are 
embodied in the amplifier to be described here. 
The satisfactory operation of the set depends 
to a great extent upon the correct design of the 
radio-frequency coupling-unit. 

The ratio of transformation is important. 
In some cases a i to i ratio is employed, but in 
the majority of cases the radio-frequency 
coupler has a step-up ratio of its own. For 
instance the primary or plate coil will be 
wound with ten turns of wire while the secon- 
dary coil will have sixty turns. This is a 6 
to i ratio between secondary and primary 
respectively. The shape and size of the coils 
also have their good and bad effects on the 
successful operation of the receiver. The 
meaning of this ratio must not be misunder- 
stood. Actually, when the number of turns 
on the primary nearly equal one half of the 
secondary, the voltage step-up is greatest but 
the neutralization becomes increasingly diffi- 
cult with the increase in size of the primary 
winding. 

When the amplifier employs coupling units 
of large physical dimensions there is danger of 
a feedback action between these several coup- 
ling units. This undesirable feedback is due 
to the magnetic fields of the coils becoming 
interlinked and interfering with each other. 
This danger is also present even when small 
coils are used, if they are placed too close 
together. The difficulty is overcome by turn- 
ing the coils at such angles to each other that 
the coupling effects between the coils of the 
transformers themselves are minimized. 

There are other methods of bringing this 
result about. In some amplifiers we find 
metal shielding which prevents feedback. 
Changing the angle of the coils is a simple 




RADIO BROADCAST Photograph 



BEHIND THE WORKS 

A general vie\v of the distribution of the parts. The Bradleystats are situated behind the tube sockets 



Radio Broadcast 



OAA, 



u 



SHOWING GRAPHICALLY, 
THE AMPLIFICATION IN SUCCESSIVE STAGES 

FIG. 3 

A graph showing the successive 
amplification in a cascade amplifier 

effective method. It is necessary to wind the 
several transformers as nearly alike as possible 
so that when the secondaries are shunted by 
condensers of a like capacity the wavelength 
range will be the same for each stage. The 
dials will then read the same. 

OSCILLATION; FEED-BACK NEUTRALIZATION 

VACUUM tubes, when connected to the 
usual grid and plate coils may be made to 
generate an oscillation whose frequency de- 
pends largely upon the inductance of the grid 
coil and capacity of the condenser shunting it. 
See Fig. 4. 

It is a well-known fact that, if a circuit em- 
bodying these characteristics were utilized, a 
miniature radio transmitter would result. 
This would be not only uncomfortable for the 
user himself because of the many-toned squeals 
set up, but an amplifier of this sort would also 
seriously affect neighboring receiving installa- 
tions because it would act as a transmitter, 
producing squeals in every receiver within 
range. This property is usually termed the 
radiation characteristic of an amplifier. 

Some means of balancing out these squeals 
must be provided. Lossers, compensators, 
traps, and reverse feed-back are sometimes 
employed but they are, as a rule, not as stable 
as the arrangement proposed here. A very 
fine form of this neutralizing system has been 
brought out by Hazeltine and Roberts. In 
their system, any tendency to oscillate is com- 
pletely neutralized or balanced out by the 
neutralizing condenser and the proper placing 
of the coils, all exerting a force on the grid of 
the tube equal and opposite to that set up by 
the action of the inter-capacity coupling of 
the tube as well as the inter-coil coupling of 
the radio-frequency transformers. An expla- 
nation in detail of this theory by Mr. W. Van 
B. Roberts, appeared in the April, 1924, and 



was repeated in the January, 1925, RADIO 
BROADCAST. 

Wiring also presents a problem to be solved 
by a careful and well planned procedure. 
Grid and plate leads should be as short as 
possible and should not be parallel to each 
other. There should not be any inductive 
loops in the filament circuit. In fact, the 
filament circuit should be finished first. Then 
the other connections to it may be made as 
short as possible. 

Soldering is an important consideration 
and should not be overlooked. Too much 
solder is just as bad as too little. Keep your 
iron evenly hot and clean all the time. Don't 
use a great quantity of soldering paste and use 
a good grade of solder. While it seems strange 
that such mechanical considerations should 
enter into a discussion of the design of radio- 
frequency amplifiers, its worth may be real- 
ized when it is considered that a poor soldering 
job will completely offset the finest design and 
assembly, and render the amplifier practically 
inoperative. 

HOW MANY STAGES? 

NOW the number of stages of radio- 
frequency amplification that may be 
successfully employed is limited by the human 
element. Two stages of radio-frequency 
amplification have become accepted as the 
maximum number that may be advantage- 
ously operated. More than this usually lowers 
the operating efficiency of the receiver. Multi- 
stage radio-frequency amplifiers have made 
their appearance on the radio-market. These 
types are usually controlled by a gear arrange- 
ment actuating the several condensers, but due 
to electrical and mechanical difficulties, have 
not become very popular. 



Inter-Coupling between 

the Grid and Plate Coil 

is afforded by the capacity 

action of the tube 



, / Represents Tube 
* Capacity 



II 1 

II i 




FIG. 4 

A circuit capable of oscillating thereby becoming 
a miniature transmitter when coupled to an antenna 



How to Build a Two-Stage Radio-Frequency Amplifier 



53 



RADIO-FREQUENCY TRANSFORMER DESIGN 

'"THE style of winding of a radio-frequency 
* coupler offers an interesting field for 
study. Spiderweb and diamond weave styles 
have lately come to the forefront of radio 
design because of the mechanical and electrical 
advantage they present and the ease with 
which they may be made and mounted. The 
same value of inductance can be provided in 
a concentrated spiderweb or diamond weave 
form which, if constructed as an ordinary 
single-layer coil would require a much larger 
space. Also, with these new inductances, 
the distributed capacity of the coil has been 
materially lowered which increases the overall 
efficiency of the unit. When the winding is 
concentrated, the magnetic field set up by the 
currents travelling through the coil is similarly 
concentrated and does not feed over into 
adjacent coil units. 

Engineers have made electrostatic coupling 
a special study. Full reports of their findings 
are not yet available. However, the few bare 
facts such as separation of parts, concentration 
of coil winding, and simplicity of wiring serve 
to guide us toward correct constructional 
design. The circuit of the radio-frequency 
amplifier described here is shown in Fig. 5. 
This amplifier may be used with any type of 
detector and audio-frequency amplifier now 
available. In a future number of RADIO 
BROADCAST we shall describe a detector and 



amplifier unit especially designed for use with 
this radio-frequency amplifier. 

This circuit consists of three tuned circuits. 
The output of the last circuit connects to the 
input of the detector tube to be used. The 
antenna and ground are connected to the 
primary of the first circuit. 

As may be seen by the several photographs 
accompanying this article, all the parts are 
mounted upon the panel and a baseboard is 
eliminated. As far as possible, the ideas 
brought out in this discussion have been 
incorporated in the amplifier unit described 
here. 

CONSTRUCTION OF THE UNIT 

MAKE the amplifier in accordance with 
these instructions, it is well to procure the 
parts as listed. Other parts of similar design 
and quality may be used with equally good re- 
sults. The use of uv-2oi-A or ov-2 tubes is re- 
commended but others such as i and 3 volt 
tubes may be satisfactorily employed. 

The coils used were made up by the F. W. 
Sickles Co. of Springfield, Mass., from specifi- 
cations supplied. For those who wish to wind 
their own, the coil data is included in the 
following pages. 

THE PANEL 

TN LOCATING the holes to be drilled in the 
* panel, it is well to lay off the dimensions 
on the rear of the panel. Otherwise the 



r 



DETECTOR CIRCUIT 
3-5Megs 




6V. A 



45 V. B 



45 V. B 



FIG. 5 



The schematic circuit diagram of the amplifier whose construction is de- 
scribed. The heavy line indicates the brass bus bar strip connections 



54 



Radio Broadcast 



r 



CM 
I 



X 
= (O 




-I 








*-<- 



^^^_y ^___ 

>k- -Jfr- -H 




^o as 

v. .5 

S^g 

" S^ 



How to Build a Two-Stage Radio-Frequency Amplifier 



55 



scriber lines, if marked on 
the front, would be visible 
and unsightly unless re- 
moved by a graining pro- 
cess. Some builders will 
wish to provide a grained 
surface on the front of the 
panel. Graining may be 
accomplished by rubbing 
the panel along its length, 
with a straight motion, 
with No. o emery cloth. 
This is continued until all 
the glossy marks on the 
panel have been removed. 
The graining process usually takes place after 
all the holes are drilled. The panel is then 
polished with an oiled cloth. 

In drilling the holes it is well to drill all of 
them first, with a No. 28 drill and then enlarge 
to the required size with the correct size drill. 
This procedure affords a more accurately 
drilled panel than if all the holes were directly 
drilled with the required size drills in the begin- 
ning. By referring to the panel layout in Fig. 
6A it will be observed which holes are to be 
countersunk. This layout should be thor- 
oughly understood before actual construction 
is begun. 

In a similar manner of layout, the binding 
post strips and brass mounting bus-bar strip 
are prepared and drilled. See Fig. 6 C, D, 
-E, and F. 

WINDING THE COILS 

THE type of coil used here is termed the 
diamond weave. To wind these coils 
it is necessary to have a cylindrical wooden 
form (a rolling pin of the required size will do) 
2! inches in diameter. Around the circum- 



-B- 




RADIO BROADCAST Photograph 
A SYMMETRICAL PANEL ARRANGEMENT 

The jack in the lovrer left is for plugging-in a loop. 
Vernier dials may be substituted for those shown 



ference of this cylinder, at approximately inch 
intervals are driven brass or wooden pins T 8 ff 
inch in diameter i| inches long. The coil 
winding form is illustrated in the sketch Fig. 
A. No. 22 d.c.c. wire is used throughout the 
windings. 

The antenna coupler has only a primary and 
secondary. The other two coil units have a 




Parts required: f 
I cylinder 2^dia. 1 wide 
35 spokes i l ,'long %'4'di 



SHOWING FIRST THREE 
TURNS ON FORM 



FIG. 7 

A. is a coil form for winding the diamond weaves. 

B. How the weave is produced. Under two, then 

over two, is the rule 



-B 2 no TURN 



FIG. 8 

Shows the first three turns in their relative positions 
to the spokes in producing a successive overlap re- 
sulting in the diamond weave coil 

double-wound primary, constituting the N-P 
coils, and a secondary (S), as illustrated in Fig-5. 

The weave of the coil is produced as out- 
lined in Figs. 78 and 8A-B-C. The first 
three turn positions are illustrated and will 
serve to indicate the progressive overlap of 
each additional layer of the winding. Suc- 
cess in this winding is all in the start. The 
beginning of the wire, allowing for a six inch 
lead, is fastened at the pin i. From there it 
is brought diagonally to 2. From around 
the outside of 2 and 3 it diagonally crosses to 4. 
Here it again goes around the outside of 4, and 
5, and so on. It will be observed from this 
that the winding style is continued over two 
and under two spokes. 

Due to the odd number of spokes, the suc- 
cessive layers progress or stagger themselves. 
This permits a winding which makes the 
position of each layer wound different from 



Radio Broadcast 



adjacent layers. So the diamond weave is 
produced. 

For the second and third radio-frequency 
couplers, the primaries must be double-wound 
to provide the neutralizing winding which is 
connected to the grid of the tube through the 
neutralizing condenser. In winding the double 
primary it is well to have two spools of wire, 
one preferably colored so as to facilitate 
identity of connections. 

Six and one half turns of the pair of wires 
are wound for the primaries of the second and 
third couplers. This ratio was selected after 
tests were conducted where 12 and 18 turn 
primaries were employed. 

The antenna primary consists of a single 
wire wound for six and a half turns. 

After the primaries are wound, the secon- 
daries are wound directly over them for forty- 
five turns in the same fashion and in the same 
direction as the primary. The inside lead or 
beginning of the secondary is started several 
spokes away from the end of the primary so 
that the leads are not too close together in the 
finished coil. 

The coil may be painted with a solution 
as a binder which has been prepared by dis- 
solving celluloid in acetone, or other "dope" 
of this nature. The best coils are made with- 
out dope and their turns are held in place 
by lacing made of ordinary grocer's white 
cord. 

To remove the coil from the form, withdraw 
all the spokes and then slide the coil off, taking 
care to prevent it from coming loose. Fig. 9 
shows how to insert the mounting screw so that 
the coil may be fastened to the brass bus bar 
running the entire length of the receiver. 

The outside turn of the secondary connects 
to this screw. The brass bus bar constitutes 



Coil 



,Coil 



Inside "S" 
Terminal 




Insulation 
Mounting Screw 



Shows position of 
Insulating Sleeve 

COIL FORM 
(Fibre, Celluloid or 
Hard Rubber 
1/2 wide) 

- - Diamond Weave Coil 



IJspss ^Insulating Sleeve 

^---Threaded Suppbrt Bushing 

(to which is connected Outside S lead) 




Brass Bus Bar 



FIG. 9 

How the coil is mounted on the brass bus bar strip 



Brass Bus Bar' 



METHOD OF ASSEMBLY OF CONDENSER, 
ANGLE BRACKET, COIL AND TERMINAL BOARD 

FIG. IO 

All the parts are sustained by means 
of the panel and angle brackets 



the negative or grounded line of the entire 
circuit. 

As may be seen from this sketch, the -^ 
mounting screw is securely fastened to the coil 
by means of washers and nuts. If it is obtain- 
able, a piece of bakelite or fibre tubing -fa inch 
in diameter may be slipped over the mounting 
screw to insulate it from the coil winding. The 
narrow strip of hard rubber or celluloid used 
as a coil form and inserted after it is wound 
is also fastened underneath the head of the 
screw and washer. 

The coil support may be a larger-diametered 
piece of tubing or a brass rod may be turned 
down if the machinery is available. But as 
little metal as possible should be used in the 
direct field of the coils. 

ASSEMBLY 

\A7ITH the panel drilled, the coils wound, 
* and all the other material on hand, the 
job of assembly may now be started. 

First the sockets, then the rheostats and 
finally the condensers are mounted on the 
panel. It is well to state here that the 
assembly directions as outlined only hold good 
for the material as listed. When other parts 
are used, the builder must employ his own 
ingenuity in producing an arrangement as 
nearly like that described as possible. 

Looking at the back of the panel, the lower 
right screw of the right and center condensers 
holding the end plate of the condensers to its 
frame is removed. Also the lower screw of 
the left condenser is removed. 

Brass angle brackets 3J| x i^ inches x 
inch are fastened, as shown in Fig. 10, to the 
condensers at the places where these screws 
have just been removed, by replacing the 
screws securing the brackets at the same time. 
It is absolutely essential that these screws be 



How to Build a Two-Stage Radio-Frequency Amplifier 



57 




RADIO BROADCAST Photograph 

A VIEW OF THE ANGLE BRACKET 
FROM THE RIGHT SIDE 

exceptionally tight, but not tight enough to 
turn off the heads, so that a positive electrical 
connection between the condenser and plate, 
angle bracket, and bus-bar strip is assured. 

Fig. 10 also shows how the binding post 
terminal strip is mounted on the bracket. 
Connections to the binding posts are made on 
the under side, and the wires are soldered to 
lugs fastened to the posts. 

Fig. 13 shows the angle at which the coils 
are placed when mounted upon the bus bar 
strip. 

WIRING 

E to the placement of the parts, the grid 
and plate leads are comparatively short 
and well separated. In fact the only long 
leads in the circuit are the filament supply 
connections. 

All connections should be soldered. Lugs 
may be used at socket and condenser terminals 
to facilitate the soldering job and this also 
permits the terminal nuts to be tightly fastened 
down on the lugs before the soldering is 
begun. Suitable wrenches for this work are 
now on the market. The wiring plan is shown 
in Fig. n. The schematic circuit diagram 
is Fig. 5. 

The jack shown in the lower left hand corner 
of the panel photograph is used for plugging-in 
the loop to the first tube circuit. This jack 
performs the function of automatically dis- 
connecting the first secondary coil from the 
tuning condenser and replacing it with the 
loop. See Fig. 14. 

The inside lead to this secondary connects 
to the blade of the jack marked No. 2. The 



outside lead connects to the brass bus bar 
negative line through the metal screw and 
support bushing. The third and fourth 
blades of the jack also connect to the negative 
bus bar. Blade No. i connects to the stator 
plates of the condenser. These points are 
made clear in Fig. 14. 

The connections to the coils are as follows: 

The antenna connects to the inside of the 
primary, the outside to the ground. The 
inside of the secondaries connect to their re- 
spective grid socket terminals, the outside 
leads being connected to the negative side of 
the filament line. The mounting screw is 
utilized and another scfew terminal provided 
as shown in Fig. 9 for the secondary leads. 
The primary leads merely project out of the 
coil. 

For the double-wound primaries, the inside 
lead of one of the pair of wires connects to the 
plate of the preceding tube. The outside end 
of the other coil connects to the 'grid through 
the neutralizing condenser. The remaining 
two leads are connected together and are 
brought to the positive B battery terminal. 

A .002 mfd. fixed condenser is. connected 
from the B terminal to the minus A terminal. 
A detector circuit (to which, of course, may be 
added several stages of audio-frequency 
amplification) is connected to the r. f. ampli- 
fier as shown in Fig. 5. for test purposes. 

OPERATING THE AMPLIFIER 

ASSUMING that uv-2oi-A's are used 
throughout (although any standard type 
of tube may be substituted) the 6 volt filament 




RADIO BROADCAST Photograph 



LEFT SIDE OF THE AMPLIFIER 

The bracket supporting the bus bar, coil, and binding 

post terminal board is clearly shown, and the jack 

mounting as well 



Radio Broadcast 




How to Build a Two-Stage Radio-Frequency Amplifier 



59 




RADIO BROADCAST Photograph 
LOOKING UP FROM UNDER 

The function of the bus bar as part of the circuit and as a support- 
ing member is clear. The sockets are of the panel mounting type 



battery is connected to the battery posts 
on the terminal board at the left of the 
amplifier (looking at the rear). From right 
to left, these posts are designated as fol- 
lows: negative filament, positive filament, 
positive B battery, grid output, negative 
filament output. 

The posts on the right terminal strip are: 
antenna and ground, from right to left. The B 
battery post is connected to the 90 volt termi- 
nal of the B battery. The other connections 
are made as shown in Fig. 5. 

With the aid of the wavelength curve shown 
in Fig. 1 2, the approximate position of the dials 
may be ascertained for a desired wavelength 



setting. Due to differences in winding the 
coils and wiring, this curve will not be accurate 
for every amplifier of this type which may be 
constructed. 

It will be observed that the antenna coupler 
condenser will tune rather broadly in compari- 
son to the other two. 

The method of tuning the amplifier would be 
to set the antenna condenser dial at the desired 
setting, referring to the curve and then slowly 
rotate the other two simultaneously through a 
small arc at approximately the same setting. 
When the sharpest point has been obtained, 
retune the antenna condenser dial for a final 
setting. 



LIST OF PARTS USED 



i Panel 7 x 14 x T \ inches @$i.oo 



3 Hammarlund Variable Condensers .00037 mfd. 
2 Federal Panel Mounting Sockets 

2 Bradleystats 

3 Sickles Coil units .... 

2 X-L Vario-densers .... 

3 Na-ald Super De-Luxe Dials 

Brass strip 

Mounting screws wire, etc. 

i Double-circuit Carter Jack 



@ 
@ 



@ 



4-75 
i .20 
i .85 

i .00 
i .00 



When the coils are home-made the supplies necessary for their winding are as follows :- 
^ Ib. No. 22 d.c.c. wire 
Bakelite or metal bushing supports 
Washers 

Insulation strip, fibre, celluloid, etc. 
Screws and nuts 



> i .00 

14.25 

2.40 

3.70 

2.OO 

3-OO 

.50 

.50 

I .OO 

'28.35 



6o 



Radio Broadcast 




RADIO BROADCAST Photograph 
A DETAILED VIEW OF THE NEUTRALIZE!* 

Part of this condenser is cut away. The turning 
of the screw, top center, varies the capacity 



NEUTRALIZING THE AMPLIFIER 

ON THE lower wavelengths it will be ob- 
served that the amplifier will go into 
oscillation more easily than on the higher 
wavelengths. 

Now, by turning the adjusting screw of the 
neutralizing condenser, up and down, a point 
may be reached where the self oscillation is 
entirely eliminated or perhaps only feebly 
present. This oscillation is recognized in the 
form of a squeal whose pitch varies. The de- 
tailed method of neutralization was fully 
described in "Notes on the Robert Circuit," 
in the January, 1925, RADIO BROADCAST. 

It is well to apply the neutralization process 
at several wavelengths, noting the position 
of the tubing for each change, so that an aver- 
age may be struck. If the amplifier works 
properly, no great difference in the several 
neutralizer settings will be noted. 

Since this circuit, is not reflected it is 
quite satisfactory to employ the standard 
neutrodyne method of neutralization. Briefly 
explained, that is as follows: A station is 
tuned-in, preferably a distant one, so that the 
signal is not as loud as a local. Then the 
first tube is removed from the socket, and one 
filament prong is covered with a slip of paper 
or spaghetti tubing, so as to insulate it when 
replaced in the socket. Now after inserting 
in the socket (the filament will not light) 
the station previously tuned-in may be heard 
faintly. Carefully retune for maximum signal 
strength, which will not be as loud as when the 



tube was lighted. Then adjust the neutraliz- 
ing condenser until the signal almost, or per- 
haps actually disappears. This tube is then 
completely neutralized and the same process 
may be applied to the next tube. As each 
tube is neutralized, the filament prong insu- 
lation is removed. 

With the condensers and coils used, as 
described, the amplifier will cover a wave- 
length range varying from 230 to 600 meters 
for the entire broadcast band. 

WHAT TO EXPECT FROM THE AMPLIFIER 

THE author does not attempt to set a 
distance limit on reception of a set using 
this amplifier when connected to a detector 
circuit. The radio public has educated itself 
to the point where it takes with a grain of 
salt the highly imaginative claims of some- 
times over-enthusiastic set designers about the 
distance range of their receivers. 

It is not our desire to put a limit on the 
reception qualities of this amplifier. Rather 
let us say that it will equal any two stage 
radio-frequency amplifier we have ever tested 



625 
600 
575 
550 
525 
500 

475 

I 

I 450 

9 

uj425 
5 400 
375 
350 

325 
300 

275 
250 
>">* 




















/ 




















/ 


















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/ 


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"0 10 20 30 40 50 60 70 80 90 100 
Cz CONDENSER SCALE 

FIG. 12 

A wavelength chart which may be 
used as an aid in locating stations 



How to Build a Two-Stage Radio-Frequency Amplifier 



61 



Condenser 



Approx. g 




FIG. 13 

To obtain complete neutralization, the coils should 
be turned at an angle to the bus bar as shown here. 
The value is approximate. Actual test will de- 
termine the correct placement 



and we've surely tested more than a few. 

This radio frequency amplifier is especially 
adaptable for use with a loop. 

In a future article the construction of a 
detector amplifier unit will be described 
which, while" it may be used with any tuner, 
is especially intended for use with the radio- 
frequency amplifier described here. 



General Additional Notes 



'"TpHE use of a loop with this amplifier wil' 
* naturally reduce the strength of received 
signals and therefore not a great deal of dis- 
tance work will be accomplished when the 
loop is used. 

However, for sharpness of tuning, and 
quality of reception, the results when a frame 
antenna is used are difficult to equal where 
local stations are being received. Loop re- 
ception on locals is desirable where tone 
quality and clarity are prime factors. The 
placement of the loop near the antenna-ground 
wires (which may be connected .together) 



loosely couple it to the antenna circuit which 
increases the volume but may effect the 
quality of reception because this connection 
will cause some static to be received when 
any is receivable. 

The tuning of the first condenser when a 
loop is used will depend largely upon the num- 
ber of turns of wire wound on the loop. 

For all practical purposes, a standard pan- 
cake loop 30 inches square, wound with 16 
turns of wire spaced f of an inch apart will 
suffice covering the entire broadcast wave- 
length band. 

If variable plate neutralizing condensers are 
used, some other means for mounting them on 
the brass bus bar strip must be arranged. It 
is not advisable to mount them on the panel 
unless such an arrangement permits of the 
use of very short leads. The adjustment of 
this neutralizer is very rarely changed, so that 
for all practical purposes, the back-of-panel 
mounting will prove quite satisfactory. 




Double Circuit Jack 
LOOP JACK DETAILS 



Rear of Jack 



FIG. 14 

When a jack is incorporated for the use of a loop, 

the circuit must be altered so that the antenna 

coupler may be automatically thrown in the circuit 

when the loop is not being used 



rHE material appearing in this magazine is fully protected by copy- 
right, and editors of periodicals are advised that unauthorized publi- 
cation of circuit diagrams, technical descriptions, and parts or the whole of 
articles, without due permission and credit, is an infraction of the law. 
Those who wish to reprint material appearing in these pages are asfed to 
communicate with the editor. 




he .listeners' -^ JPoint of View 




Good National Radio Programs Prove 
"What the Public Wants" 



THE linking of a sufficient number of 
stations to carry to uncounted lis- 
teners the WEAF programs of out- 
standing musical quality will do more 
to bring about a reform in the general charac- 
ter of all radio music 
than any other attempt 
that has yet been made 
with such an end in 
view. Not that the 
powers that rule WEAF 
had this in mind when 
establishing this wide 
connection through the 
country. Quite the 
contrary. With those 
officials it is wholly a 
matter of business, as 
all who are familiar 
with the firms who are 
putting these programs 
on the air through 
WEAF well know. But 
one could scarcely ask 
the American Tele- 
phone and Telegraph 




JOSEPH KNECHT 



Lovers of good music now glory in the op- 
portunity to hear it through their receiving 
sets on those nights when such music is spe- 
cially featured. And we are confident that 
hundreds of thousands who have until now 
always referred to such 
people as "highbrows" 
or " poseurs," are going 
to go over to these very 
ranks when they find 
through experience that 
love of good music is no 
more a pose than is the 
preference of living in a 
neighborhood where 
the surroundings are 
beautiful to the eye 
rather than in one 
where ash and garbage 
cans predominate. 

It might seem, after 
all, as if the best way to 
cure the public of a de- 
sire for the undesirable 
is to surfeit it with the 
undesirable. After 
having heard an- 



Company to give this Without whom the Waldorf Astoria would almost 

well-nigh priceless op- have to go out of business, or so it seems He has nounced, "The brches- 
long been conductor of this hotel s Concert Orches- 

Their Sunday evening programs, broadcast by * ra W1 " 



tra. 



portunity to the public 
for nothing. So, as the 
intricate question 
"Who is to Pay for Broadcasting?" apparently 
remains as far from being answered as ever, we 
may well be thankful that we have this present 
development which makes possible the hearing 
of real artists at stated times, instead of, as be- 
fore, being almost always nationally swamped 
by mediocrity or worse. 



wjz, are prime favorites with radio listeners 



play, 

'Dirty Face,' " about 
one hundred thousand 

times, they may welcome hearing that the 
Victor Talking Machine Company orchestra 
will play the "Ballet Music from 'Faust'." 
Especially will they welcome the announce- 
ment after they hear this music a sufficient 
number of times to become familiar with it. 
You see, we are taking it for granted that 



The Listener's Point of View 



63 




ANNA PINTO 

The youthful harpist who has been heard frequently 
during the season from wjz, is now "off the air" 
until fall, having gone on a well-deserved vacation 



64 



Radio Broadcast 



those who have been reveling in " Dirty 
Face" over the radio lack acquaintance with 
this ballet music which is probably as well 
known as any music of its kind ever written. 

The much-discussed question of having a 
few very high-powered stations in this country 
that would ultimately control all the broad- 
casting has met with violent opposition from 
the hundreds of stations conducted for the 
purpose of ad- 
vertising the 
products of 
the business 
firms operat- 
ing them. The 
majority of 
these stations 
are far below 
any com- 
mendable 
standard so 
far as their 
programs and 
the manner in 
which they 
are presented 
are concerned. 
Will this new 
d e v elopment 
in radio,which 
is bringing the 
best in radio 
music to far 
distantpoints, 
in time put 
these stations 
out of busi- 
ness? There 
wo u 1 d be 
nothing lost 
and a good 
deal gained 
for the public 
were this to 
come to pass. 

Does it not look as if this linking of stations 
is but another way of having the broadcasting 
within the power of the few? Be this as it 
may, developments along the right line are 
coming so rapidly that all who have deplored 
the quality of radio programs in this country 
are beginning to grow optimistic. Whether 
the methods used to bring about this change 
will be permanent, no one can say. But of 
one thing we may be absolutely assured. 
Radio music having had this upward trend, 
can never again sink to the low level that has 
so widely obtained. 




PROFESSOR MARSHALL S. BROWN 

Dean of the faculties of New York University, who has delivered interest- 
ing weekly lectures on American history from station wjz, New York 



Of great interest are the statistics given 
by John A. Holman, broadcasting manager of 
the American Telephone and Telegraph Com- 
pany relative to his opinions of the change in 
the musical taste of radio listeners during the 
past two years. In January, 1923, approxi- 
mately seventy-five per cent, of radio fans 
favored jazz. In the same month of 1924 
this percentage fell to thirty five and in 

January of 
this year to 
five per cent. 
These figures 
tell their own 
story. 

Among the 
fine programs 
regularly fea- 
tured through 
w E A F are 
those given by 
the Atwater 
Kent Com- 
pany. Have 
you noticed 
that the sing- 
ers of the 
quartet heard 
in these pro- 
grams are 
never an- 
nounced by 
name? That 
should be 
qualified b y 
saying that 
we have never 
heard them so 
announced. 
"The tenor of 
the Atwater 
Kent Quartet 
will now be 
heard in the 
solo, "On- 

away, Awake, Beloved!" And when you hear 
him sing you know that he is not an amateur 
looking for publicity through the microphone; 
indeed if he were, he would insist on having his 
name announced, "before and after." We are 
quite willing to hazard the guess that this 
quartet is made up of paid professionals and 
admirable ones at that who do not want their 
names sent out as "radio artists," a position 
that can be understood considering the present 
chaotic conditions prevailing in broadcasting. 
If this guess is a wrong one, we stand ready to 
be corrected. 



The Listeners' Point of View 



Are not the phonograph companies, as long 
as they broadcast programs made up from 
titles almost entirely taken from the titles of 
records made by each artist presented, in 
danger of a repetition that will be tiresome? 
Here is a tip for the Victor authorities. Have 
all your baritones avoid "La Paloma" for a 
time! 

Great Artists Are Coming to Radio 

UNDER no circumstances will I ever 
permit an artist under my manage- 
ment to be heard by radio. Were 
such a thing to happen without my consent, 
I would consider it ground for cancellation of 
contract and take immediate steps to bring 
that about." 

Many managers of musical artists have said 
this to the present writer. And one and all 
are now permitting, evidently gladly, the 
most famous people under their management 
to be heard over the microphone. Nor are 
these hearings con- 
fined to the pro- 
grams of the phon- 
ograph companies, 
but go so far as to 
include appear- 
ances at public 
concerts. We do 
not know that, to 
date, any complete 
public recital by 
any artist has been 
broadcast, but 
where the program 
is a mixed one, 
various artists ap- 
pearing, a portion 
at least of each 
artist's contribu- 
tion to the whole is 
given to the radio 
public. It all but 
goes to prove that 
we must either 
keep up with the 
procession or drop 
out of it altogether. 



offers of hearing and seeing these same artists 
in concert? We are of the belief that, with 
the majority of people, hearing an artist in a 
few numbers would arouse the desire to hear 
him in an entire concert if possible. 

What Happened at WTAM 

IN TH E March number of this magazine, the 
statement was made in "The Listeners' 
Point of View" that on Christmas Eve, 
"Silent Night, Holy Night," was jazzed from 
station- WTAM, Cleveland. The statement 
carried the explanation that the present writer 
did not hear this sacrilege and hotly denied it 
when first given the information, but that 
this information came from a sufficient num- 
ber of sources to seem to prove it true. It ap- 
peared at the time all the more inexcusable 
considering the standard maintained by WTAM 
which is conducted by the Willard Storage 
Battery Company. 
It is with pleasure, therefore, that we 



DOES hearing 
the phono- 
graph programs 
stimulate your de- 
sire to take advan- 
tage of the oppor- 
tunity when it 




ROSELINE GREENE 

Leading woman of the WGY Players, who is but eighteen years old, and a junior in 

the New York State College for Teachers, where she is taking the classical course. 

Her entire professional dramatic experience has been gained under Edward H. 

Smith, the director of the WGY Players 



66 



Radio Broadcast 



publish a denial of this statement received in a 
letter from Mr. S. E. Baldwin, in charge of 
broadcasting at WTAM: 

So far as we know, the only time this particular 
piece of music has been sung or played over station 
WTAM was on the night of December 24, 1924 
Christmas Eve. On that particular program it was 
played or sung some five times, being first sung by 
the Cleveland Music School Settlement, under the 
leadership of Alice Shaw Duggan. 

The second time it was sung by the Old Stone 
Church Quartet, composed of Mrs. Robert J. Kelly, 
Alice Shaw Dug- 
gan, Harold 
Branch, and Fred 
S. True. This 
quartet is prob- 
ably the best 
known church 
quartet in thecity 
of Cleveland. 

It was then 
sung by Miss 
Marie Similink, 
one of the leading 
contraltos of 
Cleveland. Later 
in the evening it 
was again sung 
by Doris Stadden 
Kaser, and at 
midnight played 
by trumpeters of 
the Cleveland 
Concert Band in 
conjunction with 
chimes from th? 
Old Stone 
Church. 

The writer was 
either present or 
listened by radio 
to the entire con- 
cert; he is per- 
fectly familiar 
with the music, 
and to the best of 

his knowledge, nothing of the kind of which you 
accuse us occurred on the night of December 24th. 

Isn't it rather unjust to publish statements of this 
kind without first taking them up with the supposed 
offender? There is a possibility that sometime you 
may be wrong. 

Frankly acknowledged. Probably a number 
of people heard more than one station at once 
at that hour, the leading fault of radio at pres- 
ent. At any rate, there is a moral in this. 
Never say it was so unless you heard it yourself. 




MAGDELINE BRARD 

A very artistic French pianist, who, although scarcely out of her 
'teens, commands the admiration of connoisseurs in both this and 
her native country. She was recently heard through station WEAF 



ABE MARTIN says: "So far I ain't no- 
ticed that any romances hev cum from 
th' publishing of radio photographs." 



Shall Broadcast Music Be Explained? 

IT WOULD be well if all the musical explana- 
tions now preceding the numbers presented 
on the Victor and Atwater Kent programs 
were completely done away with until they 
can be presented as they should. Some of us 
even go so far as to believe they should never 
be attempted under any circumstances. As 
matters now stand, they are compiled evi- 
dently from the studio dictionary by someone 
who knows nothingof the subject. They are put 

into type and 
then read by 
the announcer. 
When Toti 
Del Monte 
sang "Caro 
Nome" from 
"Rigoletto," 
the attempt to 
explain what 
the song meant 
was wholly fu- 
tile. For that 
matter, you can 
go to any of 
these early 
Verdi operas 
and never com- 
pletely know 
what the story 
is about. How, 
then, can 
Gilda's infatu- 
ation for the 
dissolute Duke 
be explained? 

Then there 
was De Luca's 
singing of 
"Largo al fac- 
totum" from 

Rossini's "Barber of Seville." We defy any- 
one who has been to see this opera one hun- 
dred times to tell the plot offhand. There 
was no attempt to tell the plot when De Luca 
gave his superlative rendition of this number, 
but there were some jumbled comments about 
his fame in the role of "Rigoletto," and then 
something about the role of the barber, 
"Figaro," in the Rossini opera. 

If something must have been said, why not 
let it go with saying that "Largo al factotum" 
is one of the most famous comic songs in all 
operatic literature, and that De Luca is un- 
excelled among living baritones in its interpre- 
tation? 



The Listeners' Point of View 




LOLA SUMMERS 

Ingenue of the WGY Players. She has been as- 
sociated with this radio dramatic company since 
their first production 

HowClassical Music Should Be Played 

WE ARE much interested in learning 
the outcome of the suit for $10,000 
damages filed by Francis E. Wood- 
ward, a music teacher of Spokane, against the 
leader of an orchestra in that city, the alleg- 
ation being that the rendition by the orchestra 
of the classical compositions of the old masters 
is such. that, "the public has received a per- 
verted idea of classical music, insofar that 
children may no longer desire a musical edu- 
cation." 

The jazzing of the classics is the greatest 
outrage perpetrated by jazz orchestras. Mr. 
Woodward assuredly had the courage of his 
convictions in entering this suit. A pity he 
could not have filed it against the city instead 
of an individual. Where the classics are 
seldom heard in their original form in public 
performance, the influence of these mutila- 
tions would be much more far-reaching than 
in Chicago or New York, let us say. Would 
that Mr. Woodward might win ten times ten 
thousand dollars! 

The Fame of Georges Bizet 

IF GEORGES BIZET, composer of "Car- 
men," and of the " L'Arlesienne Suite" so 
frequently heard over the radio from the 
better class stations could know that his 
name, through the means of broadcasting, is 
now familiar to practically the entire Ameri- 
can public, well, imagination fails to measure 
his astonishment. After meeting with little 
but failure throughout his short life, he died 



at the age of thirty-nine, a few days after his 
"Carmen", now judged by many as the one 
perfect opera ever written, was first produced. 
Three years before this he had been com- 
missioned to write incidental music to Al- 
phonse Daudet's three-act play, "L'Arle- 
sienne." The play was withdrawn after 
fifteen performances. Of the twenty-seven 
musical numbers written for this drama, Bizet 
chose various ones and from them made'a suite 
for concert use, and this was successful. The 
music, as all who have heard it know, is ex- 
quisite. It has all the elegance and finesse 
of the French school, and in the "Adagietto" 
carries the theme of sadness with such art 
that it becomes beauty rather than sorrow. 

But Bizet did not confine himself to the 
French school by any means when he wrote 
"Carmen." Here is a Spanish story trans- 
lated by a Frenchman into Spanish atmos- 
phere with music that, while although it is not 
of Spanish origin, sounds as if it were. But 
it speaks of admiration of Wagner, even more. 

June 3, 1925, will mark the fiftieth anni- 
versary of Bizet's death. After all, that is 
not so very long to have become established as 
world famous, when, in dying, success, to say 
nothing of fame, seemed a myth. 




JOHN A. HOLMAN 

Director of Broadcasting for the American Tele- 
phone and Telegraph Company. He has made a 
careful study of the preferences of radio listeners, 
judging from the letters written to the various sta- 
tions controlled by his company, and recently 
announced that public preference was swinging from 

jazz to classical music 




How to Record Radio Signals 



THERE are many occasions when it is 
desirable to make records of wireless 
reception. Figs, i, 2, and 3 illustrate 
a system of recording that is compar- 
atively simple and yet quite effective. The 
apparatus described was installed as a check 
on fading phenomena during the total eclipse 
of the sun on January 24th, 1925. 

The apparatus consists of three primary 
parts, the tuner which may be any con- 
venient set the amplifier, and the recording 
dictaphones. Two stages of amplification are 
sufficient, although 
three steps of resis- 
tance-coupled inten- 
sification with volume 
control were used in 
this laboratory. It is 
advisable to have 
some volume regula- 
tion in order to lower 
the maximum intens- 
ity below the blasting 
point of the recording 
diaphragms. 

Standard office 
dictaphones were prepared by affixing tele- 
phone receivers to the throats of the speaking 
tubes. The soft rubber fixtures intended for 
adapting head sets to horns, are convenient for 
the purpose. Two dictaphones are not re- 
quired but were employed in the RADIO BROAD- 
CAST tests to insure an unbroken record. 

The machines should be located at least five 
feet from the receiver and more if convenient, 
to eliminate motor induction. Grounding the 
frames of the machines will also reduce inter- 
ference from this source. 

It is generally desirable to monitor record- 
ing on a loud speaker. This is most easily 



In the R. B. Lab. This Month 



A Complete Article Radio Recording with a 
variety of applications, such as tracing oscillat- 
ing receiver interference, learning the radio 
code, and others. 

Shooting Trouble How we go about it. 
This article is the first of a series that will 
help the reader to solve difficulties in his receiver 
systematically and swiftly. 

Notes on Wiring Your Own Lab. 



accomplished by connecting the telephone 
receivers (clamped to the recording instru- 
ments) in series with the loud speaker. A 
shunt variable resistance, 200 to 5000 ohms, 
across the phones, provides the recommended 
volume adjustment, without greatly affect- 
ing the loud speaker. I f more convenient, any 
other satisfactory form of speaker unit may 
be substituted for the phones. 

In recording fading, it is advisable to keep 
the receiver oscillating and record the beat note 
or squeal of the distant stations. I n addition to 
the greater intensity 
and sensitivity of this 
arrangement, signal 
variations will be 
much more noticeable 
due to the fact that 
the sound will vary 
approximately as the 
square of the signal 
variations. 



OTHER USES 



ASIDE from the re- 
** cording of fading 
and swinging, this apparatus may be put to 
many other interesting and useful purposes. 
It will immediately suggest itself for record- 
ing programs of special or historical interest, 
such as the inaugural address of the President 
of the United States. Reception is affected 
in the manner described, except, of course, 
that no beat note is produced. 

LEARNING CODE 

pVlCTAPHONES have been used for some 
*~J time in the reception of high speed (80 
to 100 words per minute) radio telegraph code 
signals. For transcription, the machine is 



In the R. B. Lab. 



slowed down considerably, and the messages 
typed off at perhaps twenty words a minute. 
Speed reduction presents an excellent system 
for learning the code an acquisition which 
many broadcast enthusiasts are attempting. 
It is merely necessary to speed the machine 
slightly and record any six hundred meter 
commercial station, or two hundred meter 
amateur station, and copy the sending of the 
operator at the desired reduction. The machine 
is tireless and will give you any number of 
repetitions. 

TRACING CODE INTERFERENCE 

ALL types of interference can be logged on 
* the machines and later identified by an 
expert, as amateur interference or commercial 
code, arc-lights, leaky pole transformers, etc. 
It is only when the type of interference has been 
determined that it is possible for the radio in- 
spector to take steps to eliminate it. 

Systematic logging of all kinds of inter- 
ference for later identification by an expert 
radio telegraph code operator would go far 
toward clearing up the air. 
An identified "blooper" made to listen to 



his own mush, recorded on a neighboring 
receiver, may be thoroughly impressed with 
the iniquity of his action. 

REPRODUCING 

PHERE are two convenient ways of re- 
1 producing the radio records. The first, 
and perhaps more satisfactory method, is to 
employ the standard dictaphone transcribing 
machine, listening in the customary manner 
through the rubber tubing. The second, and 
more spectacular system, is to reproduce 
electrically, amplifying the sound and out- 
putting it to a loud speaker. This method is 
illustrated in Figs. 2 and 3. 

The arrangement as suggested in the dia- 
gram consists of three parts, the microphone 
for picking up the sound, the amplifier, and the 
talker. This apparatus may readily be a 
simple re-arrangement of the equipment em- 
ployed for recording. The microphone (of the 
magnetic type) is conveniently the telephone 
receiver or loud speaker unit clamped to the 
throat of the dictaphone adjusted for repro- 
ducing, but connected to the input instead of 
the output of the amplifier. The loud speaker 




FIG. 



Making fading records in The R. B. Lab. Beat-note fluctuations are mon- 
itored on the loud speaker and permanently recorded on the dictaphones 



Radio Broadcast 



remains in the plate circuit of Telephone 
the last tube. 

When recording and then re- 
producing in this fashion, it is 
most important that the ampli- 
fier, which is really used twice, be 
free from audible distortion. 
With the interposition of the 
several mediums, it is inevitable 
that quality will be lost, and 
every effort must be made to re- 
produce faithfully. Unless the 
experimenter is very sure of the 
results produced by his amplifier, 
resistance coupling is recom- 
mended. In the photographs, 
a three-stage resistance-coupled amplifier was 
employed for recording, and a two-stage 
transformer-coupled amplifier for reproduc- 
ing. 

The reproducing system can be readily 
applied to any phonograph arrangement 
where great volume or electrical transmission 
is desired. It is only necessary to place the 
microphone where it will intercept the sound 
waves at a point of fair concentration. A 
magnetic microphone of the type described 
is preferable to the ordinary carbon grain 
variety. 



Output 




6 V. 



FIG. 3 

The circuit diagram for the amplified reproduction of audio 

records. This system may be employed for the amplification 

and transmission of phonograph music 



SHOOTING TROUBLE 

EVERY laboratory, and every radio 
experimenter for that matter, must be 
prepared for the innumerable diffi- 
culties that beset the way of radio experiment. 
This laboratory has its full share of them; in 
fact it is part of its business. Shooting trouble 
may be simplified and thereby made more 
swift and efficient, by following a certain logi- 
cal procedure. A doctor does not treat his 
patients in a haphazard manner. He does not 
tap them on the chest when they have a tooth- 




FIG. 2 



The amplifying arrangement for reproducing the records on the loud speaker. The telephone re- 
ceivers or loud speakers employed for recording may be used as pick-up microphones in reproducing 



In the R. B. Lab. 



ache, but rather he observes the symptoms and 
through a sequence of thought and experiment 
establishes just what and where the trouble is. 
Likewise in radio a few consistent observations, 
even by the most unexpert member of the 
family, will often solve the difficulty without 
calling in an expert. 

There are three types of radio difficulties: 

Absolute Inoperation 
Poor Operation 

Noises 

These are general headings and they cover a 
multitude of the conventional radio sins. In 
this article we shall begin to treat the first 
group, not because it is the most prevalent 
(which is doubtful) but because its treatment 
is the more definite and simple. 

THE SET WON'T WORK 

OERHAPS the receiver is turned on in the 
* usual manner but nothing happens. The 
receivers or loud speaker is dead, and the 
twisting of dials futile. The first thing to be 
done is to locate the trouble. The second 



task to be treated next month is to apply 
the remedy associated with that particular 
trouble. 

Test No. i Turn off the bulbs, listening for 
a click in the phones or speaker. No click in- 
dicates a break somewhere in some battery 
circuit. When there is no click, we proceed to 

Test No. 2 Inspect the bulbs. If they 
light, the filament circuit is O. K. A very dim, 
partial light (which however, should give a 
faint click in Test No. i) suggests a low A 
battery. One or more bulbs may be " blown ". 
If the bulbs do not light we try 

Test No. 3 Make a momentary "short" of 
the binding posts on the set generally marked 
A-pIus and A-minus, with a pair of scissors or 
any other metal object that is convenient. A 
spark indicates trouble in the set itself fila- 
ment wiring, burnt-out rheostats, loose socket 
prongs, filament control jack, or an inoper- 
ative switch. No spark shows that the trouble 
is on the battery side in the leads to the 
battery, in the battery terminals, or a dead 
battery. 

If Test No. 2 finds the bulbs normally 




FIG. 4 

"There is no spark, Harry, You 'd better take a look at those battery leads". There are many simple tests 

that almost any one can make which will show up the more common radio ailments, and suggest a way to 

remedy the difficulty without calling in an expert 



Radio Broadcast 




FIG. 5 

If the bulbs light, pull the plug out, listening for a click in the loud speaker or phones. When these simple 
tests do not actually show you the way out of your difficulty, a description of the results will be of very 
great benefit to the Grid Department, or to your local expert in helping you out 



lighted, the plate circuit in the last tube is, 
probably open. This may be additionally 
ascertained by 

Test No. 4. Pull the phone plug in and out, 
listening for a click. Change from phones to 
loud speaker and repeat the test. This will 
place the difficulty in either the output instru- 
ment or within the set. If one pair of tele- 
phones give a click in response, it is evident 
that the difficulty lies in the other. If the 
trouble is in the receiver proper, and neither 
phones or speaker work, try 

Test No. 5 Place another tube in the last 
socket and repeat Test No. 4. No response 
absolves the tube, placing the blame on an 
open B battery circuit, with the probability 
that the phones and speaker are in good con- 
( dition. 

Test No. 6 This should be in the form of a 
momentary short, or, better, a voltmeter test 
across the B battery posts on the set. If 
current is indicated, this shows the trouble is 
within the set; the current from the battery 
has succeeded in traveling as far as the binding 
posts. No deflection on the voltmeter or spark, 
if the voltmeter is not used, locates the diffi- 
culty on the battery side. 



If tests No. i or No. 4 show that there is a 
plate circuit, that the batteries are O. K., the 
next test on non-regenerative sets (neutrodynes 
and stabilized radio frequency) is 

Test No. 7 It is then possible that there are 
no receivable stations on, which means that 
they are off schedule or shut down by an sos. 
More than one fan has decimated his set dur- 
ing the enforced silence accompanying a dis- 
tress call at sea. Have someone ring your 
doorbell, or turn on and off your electric light, 
respectively while you listen for a rough buzz 
or clicks in the receivers or loud speaker. 
These will indicate that in all probability 
everything is O. K., or that the trouble is in the 
antenna or ground connections. No results 
or results below normal, suggest the radio 
frequency circuit is the source of difficulty. 

Test No. 8 With regenerative receivers, 
those employing detector feed-back and po- 
tentiometer or similarly controlled radio fre- 
quency circuits, this test will probably precede 
test No. 7. Turn up the regenerative or 
"volume" control. The usual oscillations, 
" plops ","or squeal, show that the regenerative 
detector and audio frequency tubes are O. K. 
The operator will then proceed to Test No. 



In the R. B. Lab 



73 



7. Negative results from Test No. 8 show a 
fault in the regenerative tube or tubes or in 
any of the audio stages except the last, which 
Tests i and 4 proved O. K. 

Test No. g Tap the bulbs with a pencil, 
moving progressively toward the antenna 
connection. This generally means from right 
to left: second audio, first audio, detector, 
etc. No ring will be heard in the loud speaker 
when the faulty tube or stage is reached. 

Test No. 10 Changing tubes will almost 
always eliminate or define the bulbs as the 
source of difficulty. 

Try all these tests when your set is working, 
immediately when the trouble is discovered if 
possible, in order to acquaint yourself with the 
response you may expect from a working re- 
ceiver. 

BUILDING YOUR OWN LAB 

WIRE your lab. with an eye for con- 
venience in testing and operating 
more than one receiver in different 
parts of the laboratory. The arrangement de- 
veloped in the R. B. LAB can be enlarged or 
reduced to suit individual convenience. 



Filament and plate batteries are centrally 
located with charging apparatus, and are 
wired to the benches using colored wire, often 
called "code wire." 

Six outlets are desirable, which provide for 
the connections to as many receivers or test 
apparatus. Seven wires are used. Two differ- 
ently colored heavy stranded wires carry the 
A battery current. Four No. 18 annunciator 
wires of variegated hues, provide plus B 
battery from 22\ to 140 volts. The negative 
B is connected to positive A on the battery 
table.. The seventh wire connects to an out- 
side antenna which may be disconnected by a 
switch at each of the six outlets. 

One hundred and ten volt lines are run in 
metal moulding along the edges of the benches 
with similar outlets. The moulding itself 
affords the ground. The moulding should be 
installed according to underwriter's require- 
ments, who, however, have no jurisdiction 
over the other wiring. 

If desired, fuses, switches, and meters (volt, 
ampere and milli-ampere), can be installed at 
the battery table. Several photographs 
taken in the Lab. depict the utility of this 
arrangement. 




FIG. 6 

Tap the bulbs and listen for the usual ring. A ring from any of 
the r. f. or detector tubes shows that the audio amplifier is O. K. 




ike troc|c[cc|ster sees xi 




Drawings by Franklyn F. Stratford 



How Much Power is "Super-Power"? 



HOW big must a broadcasting station 
be to claim attention as a "super- 
power" outfit? Estimates appear 
to vary. The owners and publicity 
representatives of the j-kw transmitters now 
being put into operation in various sections of 
the country like to refer to them as super- 
power equipment. But if 5 kw is super- 
power, what would 50 kw be? We had better 
be careful, or we shall run out of awe-inspiring 
prefixes. It is certain that Mr. David Sarnoff, 
who is responsible for the idea and for the 
spreading abroad of the term, had a consider- 
ably greater magnitude in mind than 5 kw. 
However that may be, it is a fact that 
the power rating of present-day broadcasting 
stations is trifling compared to that of the 
great transoceanic and transcontinental radio 
telegraph installations. One of these immense 
transmitters is described in a paper by Dr. 
Cornelius J. DeGroot in the December, 1924, 
number of the Proceedings of the Institute of 
Radio Engineers, "The High-Power Station 
at Malabar, Java." This station connects 
the Dutch East Indies directly with Holland, 
arc transmitters being used in the main. At 
the present time 2,400 kw is the power supply 
to the arcs, whereby 1,200 kw are fed to the 
antenna, as compared to 0.5 kw in the antenna 
of a standard Class B broadcasting station. 
1,200 kilowatts! Ten years ago all the man- 
made radio frequency energy in the world 
probably did not amount to 1,200 kw. Dr. 
DeGroot is not satisfied, however. He assures 
us that when he gets another motor generator 
from the General Electric Company he will 
be able to supply 3,200 kw to his arcs, obtain- 
ing about i, 600 kw in the antenna. This will 



put the station on a 2o-hour-a-day basis of 
communication over its 7,5oo-mile circuit, 
which is in excess of the traffic requirements. 

But, simply regarded as power, 1,200 or 
i, 600 kw are not figures to arouse respect 
among power engineers. In a good-sized 
power plant, such as one of those which supply 
energy for the subways of New York City, the 
wattmeter reads in the neighborhood of 
100,000 kilowatts on normal load, and this 
load fluctuates 5,000 up and down. The 
mere variation in the load carried by such a 
plant is far greater than the maximum output 
of the largest radio station in existence. 

The comparison is instructive, and chasten- 
ing to the pride of the radio engineer, but at 
bottom it really does not mean much, for the 
commodities are not in the same class. Raw 
electric energy is one thing, and modulated 
radio energy especially that voice or musi- 
cally modulated is quite another. Moreover, 
this difference between simplicity and com- 
plexity is only the first of a number of unlike- 
nesses. There is a difference in reception, for 
one thing. The subway train or the electric 
toaster takes power from the line and uses it 
up. Radio receiving sets, in general, amplify, 
sometimes very greatly, the quantity of energy 
which they pick up. A super-heterodyne in 
robust form may possess a voltage-amplifying 
capacity of from 5,000 to ro.ooo times, accord- 
ing to Mr. Armstrong (from 25 to 100 million 
times energy amplification), and no doubt 
many receivers of more plebeian types have an 
energy amplification of millions of times 
(energy amplification is the square of voltage 
or current amplification). It should be noted 
that this development of receiving amplifiers 



As the Broadcaster Sees It 



75 



has been necessitated by the great attenu- 
ation involved in radio transmission, the 
losses in the intervening medium being far 
greater than those of an electric power trans- 
mission network. 

But the principal distinction lies in the 
extraordinarily small amount of energy re- 
quired to satisfy the human ear. "The speech 
energy output of the normal voice has been 
found to be at the rate of about 125 ergs per 
second. If we could have a million persons 
talking steadily and convert the energy of the 
voice vibrations into heat, they would have to 
talk for an hour and a half to produce enough 
heat to make a cup of tea. This merely serves 
to illustrate that in terms of power or energy 
human speech is exceedingly weak. Further- 
more, most of this energy is carried by the 
vowel sounds. At the upper and lower limits 
of audition it takes about a hundred million 
times as much energy to enable one to hear as 
it does in the range of 1,000 to 5,000 cycles, 
where the ear is most sensitive. At all frequen- 
cies, the energy required is small, and in the 
most favorable region the minimum audible 
tone corresponds to a pressure change per 
square centimeter of about o.ooi of a dyne. 
This pressure is roughly equivalent to the 
weight of a section of a human hair about one 
thousandth of an inch long (about one third 
as long as its diameter)." (R. L. Jones: 
"The Nature of Language." Journal 
A. I. E. E., April, 1924.) 

Thus a public address system or a moderate- 
powered broadcasting transmitter may, as 
has been pointed out, contain more speech 
energy than all the inhabitants of the globe 
yelling with all their might and main at the 
same instant if they could be persuaded to 
cooperate to this extent, which I doubt. It 
is for this reason, basically, that wireless 
stations are 
not, relatively 
speaking, 
powerful. 
They need not 
be as powerful 
as agencies 
which light 
homes or 
transport 
freight or 
press trousers, 
because these 
actions re- 
quire i n fi - 
nitely more 
energy than 



speech and hearing, and it is in hearing 
that radio communication usually terminates. 
That is why super-power in electrical en- 
gineering the section-wide coordination and 
integration of power generating facilities 
deals with magnitudes enormously greater 
than the super-power projects of radio broad- 
casting. The latter, however, assume impos- 
ing proportions as soon as we compare them 
with the energy levels of unaided speech or 
the general run of sounds found in nature. 



SUPER-SEX 

A 

SUPER 
DRAMA 




Since writing the above I have come across 
two newspaper articles bearing on this sub- 
ject. One of them is a publicity release by 
Mr. J. D. R. Freed, also pointing out that 
"super-power" is a term too loosely and 
inflatedly used in radio at the present time. 
Mr. Freed compares the power of a large 
broadcasting station like WEAF, with 2 kilo- 
watts in the antenna, with the 665 kilowatts 
consumed by a ten-car subway train (presum- 
ably this is starting energy). An electric 
sign on Broadway consumes 263 kilowatts. 
The average broadcasting station of to-day 
puts into the antenna only about as much 
power as one needs to light a six-room flat. 
Mr. Freed's idea of super-power is from 1000 
to 10,000 kw for an international program dis- 
tribution. In other words, he would go up; 
to and above the level of the Malabar trans- 
mitter of Dr. DeGroot. The only question 
we raise at this point is : Who is going to put up 
the money? Also, in his comparison of power 
magnitudes, Mr. Freed does not discuss the 
bearing of the relatively minute energy re- 
quired by electro-acoustic devices, on the 
problem of radio power. 

However, Mr. Freed is an engineer and 
what he says is sound and pertinent. At the 
opposite extreme is a publicity release by a 

radio and 
phonograph 
company 
which is about 
to enter the 
broadcasting 
field with a 
"station of 
tremendous 
power. It is 
said that it 
will have a 
range of from 
15,000 to 
20,000 miles." 
And what is 
going to be 



super" mean? 



7 6 



Radio Broadcast 



the power of this colossus? Answer^ kw. 
You may breathe again. 

Moreover, the engineer of the company in- 
forms the world that this new station will "in- 
fluence profoundly broadcasting in daylight." 
This gives the impression, to the lay reader, 
that the daylight range of a 5 kw transmitter 
must be somewhat comparable with the night 
range of the present order of figure o .5 kw 
sets. This belief is entirely erroneous. 

Messrs. H. W. Nichols and Lloyd Espen- 
schied, two prominent radio and telephone 
engineers, investigated this subject some 
years ago, in the course of a larger work which 
occupied them at that time, and reported 
their results in a scientific paper. (Nichols 
and Espenschied: "Radio Extension of the 
Telephone System to Ships at Sea," Proc. 
I. R. E., Vol. XI, No. 3, June, 1923.) They 
made actual measurements. It was found 
that in order to equal during daylight the freak 
ranges secured by radio telephone stations on 
broadcasting wavelengths (then 360 and 400 
meters) during the most favorable times at 
night, about 10,000 times as much power 
would be required. A 0.5 kilowatt station 
would have to raise its power to 5000 kilo- 
watts! 

But what's a little multiplier like 1000 to a 
publicity representative and radio engineer, 
model 1925? Less than nothing, for these 
gentry never heard of Nichols and Espenschied 
and Alexanderson and Wien and Braun and 
Armstrong and Latour and DeForest and the 
few hundred other earnest engineers whose 
exclusive creation radio broadcasting is. And, 
if they have heard of them, they care no 




vVe iveecL drtistic micropKoives 



more for scientifically derived data than the 
Long Island fanatics who recently awaited 
the end of the world. 

Artistic Stands for the Microphone 

THE design of microphone stands, at 
the present time, is far too con- 
ventional. They are tame, unimagi- 
native things wrought of bronze pipes or one- 
time respectable parlor lamps. This has 
a depressing effect on the whole broadcasting 
art, for the general public gets its ideas of 
radio largely from the myriads of pictures 
showing the great, and the aspirants to great- 
ness, posed before a microphone stand in the 
attitude of talking to 10,000,000 fellow 
citizens even when the station power is about 
10 watts. What an opportunity is neglected 
here! The future belongs to the genius who 
will express himself through radio microphone 
stands, fitting them to special situations, 
somewhat as follows: 

A ravishing silver-plated girl in attractive 
deshabille for lecturers on literary censorship, 
denouncers of the younger generation and pet- 
ting parties, etc. 

For Mayor John F. Hylan of New York 
City, a bust of Gen. John F. O'Ryan, his 
opponent in the local traction controversy. 
General O'Ryan could hold the microphone in 
his teeth. 

A foaming stein or champagne bottle for 
prohibitionists. 

At woe, the learned chiropractors might 
talk to a mound of issues of the Journal of the 
American Medical Association, the microphone 
surmounting the same. 

For Messrs. Arthur Lynch, Willis K. 
Wing, and Zeh Bouck, the desperate crusaders 
for a squealless ether, what could be more 
appropriate than a giganticdiagram of a single- 
circuit regenerator, rampant, with the micro- 
phone suspended from the oscillations? 

The ramifications of the idea are obvious. 
Its inspirational properties are unlimited. 
We leave its execution to philanthropists and 
artists. 

Note on Announcing 

A COMMITTEE has recently been occu- 
pied, in New York City, with the task 
of raising the standards of announc- 
ing. Various conclusions as to rate, pitch, 
inflections, and other characteristics were 
reached and duly published. 

A most praiseworthy work. But the com- 
mittee omitted consideration of one funda- 



As the Broadcaster Sees It 



77 



mental fault with which nine announcers out 
of ten are afflicted: they talk too much. 

How and Why Stations Heterodyne 
One Another 

THE problem of heterodyne interference 
between broadcasting stations has the 
same origin as the rush hour jam in a 
large city: too many people are in the same 
place at the same time. 

Class B stations are supposed to be 
spaced ten kilocycles apart, with an effort 
being made to reduce the separation to 7^ 
cycles, in order to create additional chan- 
nels for new stations. These are theoretical 
separations, conditioned on all the stations 
keeping their exact assigned frequency. Un- 
fortunately, they vary. When they get a few 
thousand cycles apart, all the listeners within 
range of both hear a beat-note, a continuous 
melancholy whistle, varying slightly in pitch 
from minute to minute, and well calculated 
to drive sensitive persons crazy although, 
through the psychological phenomenon of 
auditory fatigue, some people get used to the 
beat and hardly hear it after a time, unless it 
is very loud. 

As a matter of fact, any two or any number 
of stations, for that matter have a beat note 
in any receiver capable of picking up their 
waves. If they are 10 kilocycles apart, they 
have a beat note of 10 kilocycles, or 10,000 
cycles, which is over twice as high as the 
highest note on a piano. This pitch is too 
high to pass effectively through the audio- 
amplifying circuits of a receiver, and what 
little does get through is suppressed by the 
loud speaker and the human ear, neither of 
which is designed to respond ardently to such 
an acute note. In short, nothing is heard. 
But as the two stations, through the deviation 
of one or the other, or both, from its or their 
assigned frequency, approach each other, the 
beat note between them passes into the band 
of audible and essential frequencies to which 
the acoustic apparatus of the receiver and 
listener responds. The resulting interference 
may be anything from a very shrill whistle 
up around 4000 cycles, scarcely audible to 
one not listening for it, down to an angry 
recurrent growl on either side of zero-beats, if 
the two stations happen to be right on the 
same wavelength. Or, it may be a loud, con- 
tinuous whistle of medium musical pitch. 
Loudness depends on the strength of the 
electric fields of the two interfering stations at 
the heterodyning location; pitch depends on 




clowiv staiioiv. xnierJference 



their respective frequencies and the variations 
therein. The ultimate result is telephone and 
telegraph calls from irate listeners. 

Unfortunately, a station which is too weak 
to produce a workable signal in a given 
neighborhood, is perfectly capable of giving 
rise to heterodyne interference with stations 
supplying a powerful signal to the locality 
on which it depends for program service. 
This is one of the inherent traits of heterodyne 
amplification, the same which enables an 
oscillating receiver to hold a very audible beat- 
note with a distant station, while, in the non- 
oscillating condition, the modulation of the 
station in question is inaudible a character- 
istic which is therefore responsible for the 
reprehensible use of beat reception by users 
of radiating receivers. Great is heterodyne 
amplification, and, like many other great 
things, it is also capable of causing a deal of 
mischief. 

The result is that in, say, New York City, 
you may be listening to one of the local 
stations five or ten miles distant, employing 
enough amplification to get a comfortable 
signal; and although in that condition your 
set could not possibly hear a Chicago broad- 
caster of the same power, when that Chicago 
station climbs on to your New York station's 
wavelength, you get a beat-note of perhaps a 
quarter the intensity of the local station's 
signal. (Living in New York, and being 
responsible for the technical operation of two 
of the local broadcasters, I naturally assume, 
and stand ready to prove it with wavemeters 
and firearms, that the Chicago station is at 



Radio Broadcast 



fault.) But if the New York broadcaster 
then takes his carrier off the air, and you let 
your receiver alone, there is silence. You 
have to bring up your amplification in order 
to hear Chicago. 

This has an important bearing on the prob- 
lem of running down heterodyne interference 
when it does occur. The only receiver which 
can be safely used in such work is one which 
has a volume control independent of the 
frequency adjustments. If the tuning and 
intensity controls are electrically interlinked, 
I should say that the receiver is worthless 
for detective equipment. 

If you are near one of the heterodyning 
transmitters, you are not likely to be able to 
identify the more distant one unless Number 
i takes his carrier off the air. If the inter- 
ference is serious, and the transmission of the 
station is properly monitored from a point 
outside the studio, this is likely to be done. 
The engineers are waking up to the fact that 
they can best solve their station-interference 
problems by direct action, by exchange of 
telegrams between the broadcasters involved, 
as soon as the trouble starts. The telegraph 
companies are generally willing to give priority 
to such messages. It is preferable to take the 
carrier off the air for a few minutes, for the 
purpose of identifying the interfering station, 
and to send him a telegram explaining the 
situation, rather than to suffer the con- 
dition to continue and to allow the program 
to be hashed up, in greater or less degree, for 
the entire evening. 

It is customary, when shutting down for 
this purpose, to take the listeners into one's 
confidence and to solicit their aid, for, with 
the great natural variations in receiving con- 
ditions, quite possibly some outsider will be 
able to do the job better than the one or two 
members of the station personnel engaged in 
chasing down the trouble. The purpose of this 
article is to give listeners some data which will 
make their testimony reliable in this regard. 

The rules of the game may be summarized 
as follows: 

1. When the announcement goes out, tune your 
set precisely to the wavelength of the local broad- 
caster who complains of the interference. This can 
usually be done in the few remaining seconds of 
transmission. 

2. If you are receiving on a loud speaker, change 
to head telephones; your chances with the phones 
are obviously better. 

3. When the carrier goes off the air, bring up 
your volume control till the interfering station is 
readable. Don't touch the frequency controls. 

4. If you are able, under these conditions, to 



make a positive identification, and you feel inclined 
to do that much for the cause, dispatch a telegram 
to the party of the first part who has gone off the air. 
The next best thing is to write a letter. 

5. If the intensity and wavelength (frequency) 
controls of your set are not perfectly free from inter- 
action, or if you are not confident that your set 
tunes very sharply, you can be of greatest service by 
staying out of the controversy. Your testimony 
will only confuse the issue. 

Of course, if you have a set accurately 
calibrated in kilocycles, it may be permissible 
to try to determine the actual frequencies of 
the stations involved, but with ordinary 
equipment one is not justified in testifying that 
Station Number 2 was actually on the wave- 
length of Station Number i unless the fre- 
quency-determining elements of the receiver 
remained unchanged. Even this, of course, 
is only a beginning, for Station Number i 
may have been off his wave. Once it has been 
established, however, which stations have 
been involved, it is usually possible to clear up 
the situation for the time being, and the accu- 
rate calibration of their frequency indicators 
must be left to the Federal radio supervisors. 

The necessity of instructing the l : sieners in 
the above procedure, if they are to be of service 
in these situations, was brought home to me by 
a recent incident. I was listening at my 
home when one of the stations in which I am 
interested developed heterodyne interference 
early in the evening. Program complications 
made it inadvisable to interrupt the service 
later, so I telephoned immediately and had 
the carrier taken off the air for four minutes. 
Before these instructions could be carried out 
the interfering station shifted his wavelength, 
and the beat-note ceased. It was too late to 
cancel the order, and the carrier went off. I 
listened on the chance that the distant station 
might come in again during the four-minute 
period of observation, but heard nothing 
except two extremely distant transmitters 
heterodyning each other, and a spark station 
in the English Channel. As soon as the 
carrier went back on the air, Dr. Alfred N. 
Goldsmith telephoned me to say that he also 
had heard nothing to indicate that any one 
was on our wavelength, and that on his 
specially calibrated super-heterodyne both of 
the out-of-town stations which occasionally 
clash with us were on their assigned frequen- 
cies. Dr. Goldsmith is the chief broadcast 
engineer of the largest radio company in 
the world, and has been making precision 
measurements in radio for about fifteen years, 
so that what he says must be accepted as ex 



As the Broadcaster Sees It 



79 



cathedra. But a considerable number of 
listeners notified the station that X and Y, 
the two transmitters with which we some- 
times have difficulty, were on our wavelength. 
We know that at this particular time X and Y 
were innocent. Clearly our well-meaning 
informants were wrong in their conclusions. 
As long as only two stations heterodyne each 
other, there is hope, but in the not infrequent 
case where three transmitters are involved, 
one can do little but sit back and stand the 
gaff. Generally, when one carrier is taken off 
the air, the remaining two beat with each 
other to such a degree that the announcements 
of neither can be understood. The only thing 
that a broadcaster in this situation could do 
would be to shift his own wavelength and get 
clear of them both. But that is reprehensible, 
for if individuals start taking the law or the 
wavelength into their own hands in this way, 
the present difficulties of ether congestion will 
become aggravated to the point of chaos. 
Such a remedy is worse, in the long run, than 
the disease. Communication and cooperation 
between broadcasters should all be in the 
direction of keeping every one on his assigned 
frequency. If the stations will only stay put, 
we shall be able to say, as far as beat interfer- 
ence is concerned, "The rest is silence." 

Who is Which in Radio- 
Colonel Combust 

ON OUR recent trip abroad we carried 
letters of introduction to Colonel 
Combust, the Chief Signal Officer of 
the unmatched Euphratean army. We had 
considerable difficulty catching up with 
Colonel Combust, for the Euphratean forces 
were just then retreating before the matchless 
Kustanian army, a war having sprung up 
between the two monarchies over a chorus 
girl. Finally the officer was located, standing 
up to his mustache in a river, and waving his 
sword to encourage the brave Euphrateans 
who were swimming around him. Delivering 
our letters through an orderly, we hove to in 
our rowboat, waiting for a statement. 

"We shall deceive the enemy," cried the 
gallant colonel, "for the code our signal corps 
operators send is absolutely unrecognizable, 
even by ourselves. Therefore the cursed 
Kustanians will be unable to discover our 
designs, our arms will triumph, and the lovely 
chorus girl Tina will be restored to the Eu- 
phratean "Follies," from which she was want- 
only kidnapped by the King of Kustania, that 
insolent pig!" 



As the valiant colonel swung his sword close 
to our nose during this denunciation, we 
rowed several boat-lengths upstream before 
asking: 

"Has the King of Kustania no chorus girls 
in his own dominions?" 

"He has," explained the colonel, "but his 
taste in that line is exotic, like that of a DX 
hunter, who praises the stations of every 
country but his own." 

"Are you, then, afflicted with broadcasting 
stations, sir?" we inquired. 

"Yes, indeed," answered Colonel Combust, 
"and 1 predict with confidence that, after we 
have defeated the enemy in this present war 
over Tina, the next war between Euphratea 
and Kustania will be brought about by the 
broadcasting stations." 

"What!" we cried. "We understood that 
broadcasting was to lead to universal peace, 
the hearts of the Mongolians, Californians, 
and Esthonians being softened by mutual 
listening to bedtime stories, lectures on the 
dog-collar industry, and reports on measure- 
ments of the losses in No-Loss variable 
condensers. Nay, more, we had worked out a 
plan whereby all international disputes were 
to be settled, not by citizens shedding each 
other's blood, but by the announcers of the 
several countries being allowed and incited 
to talk each other to death. Thus an orderly 
and beneficial process would be substituted 
for barbarous warfare. What could be sweeter 
than to have the announcers die for their 
countries, while other citizens continue to hug 
their girls 

"Whose girls the announcers'?" inter- 
rupted the colonel with great interest. 

"Announcers have no girls," we exclaimed 
impatiently. "The conjugal tie cannot long 
unite two such verbose entities as a woman 
and an announcer, and girls, realizing this 




ike Lo<jt osciUdtetl like <l Hooper 



8o 



Radio Broadcast 



fact, do not waste their time on the gentlemen 
of this trade." 

"Nature is wonderful," agreed the doughty 
officer. 

"As we were saying," we continued, "the 
announcers will perish, but respectable real- 
tors, cheese-brokers, and clothing dealers will 
continue to drink chocolate sodas and to roll 
the bones. No longer will war ravage and 
impoverish countries. Such, at least, was my 
plan and expectation. And now you, Colonel, 
tell me that the great nations of Euphratea 
and Kustania are on the brink of another 
war when they finish the present one over 
a question of broadcasting stations! Oh, 
Colonel 

Such was our agitation that we stood up in 
the rowboat. 

"Sit down," called the officer. "You are 
rocking the boat." 

Indeed, the boat was oscillating like the 
single-circuit receiver owned by the janitor's 
little boy. We sat down. 

"Nothing could be more natural," Colonel 
Combust asserted. "The Euphratean engi- 
neers having erected a 3-kilowatt station, 
immediately the greasy Kustanians proceeded 
to put up one of 10 kilowatts. Is not that a 
casus belli ? Shall we hesitate to defend 
our national honor?" 

"But, sir," we assured him, "does any one 
doubt that three Euphratian kilowatts are 
worth ten Kustanian kilowatts?" 

"Absolutely," cried the Colonel. "But 
you should hear the modulation. It is an 
atrocity, The whole world should make war 
on a country which permits such distortions 
in the ether." 

"Don't say that, Colonel! On that basis, 
will not the League of Nations attack Newark, 
New Jersey, and stab it in the lower wave- 
lengths?" 




committees are iu 



ciimouiicers 



"Why not?" inquired Colonel Combust, un- 
disturbed, as ever, at the prospect of another 
war. "The surrounding marshes will be 
eternally grateful to any power which delivers 
them from some of those Class A coffee- 
grinder broadcasters." 

" Besides," he continued, reverting to his 
favorite subject of the disputes between 
Euphratea and its hostile neighbor, "why 
should Kustania have a broadcasting station 
at all? The miserable Kustanian goatherds 
have no more valid use for such an apparatus 
than a football player has for a brassiere." 

"Are they deaf and dumb, then?" we asked. 

"No," answered our informant, "although 
it would be a blessing if they were. You 
should hear their so-called broadcasting. 
What uncouth speech! What asinine argu- 
ments! What unadulterated drivel! Music 
such as little children make on their drums 
and fish-horns on Christmas! It is indescrib- 
able. One must hear it. But, as you seem a 
well-meaning and moral young man, I pray 
that you may be preserved from such an 
ordeal." 

"Colonel, you speak exactly like one broad- 
caster about another in the same town in my 
country. They refer to each other, recipro- 
cally, in such sweet terms. But this is a 
conflict which we cannot resolve at the present 
time. So tell me, Colonel, would it not be 
possible for you to issue forth from this river 
and have dinner with me in that town I see on 
the horizon?" 

"It would be bad tactics," answered the 
immersed officer, regretfully. "We have 
strategically placed our superb army in this 
river because the despicable Kustanians have 
60,000 more men .than we. But, such is their 
fear of being washed, that they will not ven- 
ture near a body of water of this size. Thus 
by remaining in the river we are carrying the 
war to a glorious conclusion." 

"The sensation of hunger," writes the 
physiologist Cannon, ". . . may take 
imperious control of human actions." A 
journalist is human. Hunger forced us to 
take leave of the heroic Colonel Combust 
and the other brave Euphrateans. When we 
had rowed about fifty feet towards the shore 
the Colonel hailed us. 

"Sir, will you grant me a great favor?" he 
called. " Bring me back a ham sandwich and 
a water-proof radio receiver." 

"Why the radio receiver?" we asked. 
"Would you not rather have two ham sand- 
wiches?" 

"No," answered the valiant soldier pile- 



As the Broadcaster Sees It 



81 



ously, "my feet are cold, and 1 would warm 
them by listening to the strains of 'Red Hot 
Mamma' broadcast nightly by 500 American 
stations." 

Unfortunately, when we returned the river 
had frozen over from shore to shore, and no 
sign remained of the great-hearted colonel and 
his army. Furthermore, the Kustanians beat 
us up to within an inch of our lives for afford- 
ing assistance to the enemy. We are proud, 
therefore, to present to our readers this last 
interview with Colonel Combust. Requiescat 
in pace which, translated, means, May he 
freeze in peace. 

Why Should Radio Appeal Only to 
the Auditory Sense? 

THE quotation with which we are now 
about to grace this crude and material- 
istic department is ladled out from the 
daily sugarwater offering of a metropolitan 
radio critic: 

Deferring to the guest of honor's habitual aversion 
to radio, broadcasting forces had tactfully concealed 
the microphone among masses of flowers. Their 
sweet odor was infused into the words of the speak- 
ers, which transmitted with unusual clarity in spite 
of the blossomy screen. 

A sweet odor was infused into the words of 
the speakers, ladies and gentlemen. Observe 
that honeyed figure of speech. 

However, this is not the time to make my 
confessions in full. What I started out to 
develop was a speculation on the relation of 
radio to the various senses of a human being, 
as suggested by the above quotation. Is it 
conceivable that odors will ever actually be 
transmitted by radio? It certainly is. In 
radio telephony we start with a microphone, 
which changes sound waves to electrical 
impulses; the rest is easy. In the photo- 
radiogram processes which have recently been 
demonstrated, we allow light to impinge on a 
photoelectric cell, the light waves are trans- 
formed into electrical fluctuations, and photo- 
graphs are sent over the ocean. Anything 
that can be translated into electrical energy 
can be transmitted by radio. Hence why not 
smells? The sense of smell involves the 
chemical action of vapors, essences, gases, or 
finely divided particles brought into contact 
with special organs of sense, the olfactory 
nerves. All we have to do is to invent an 
olfactory-electric cell, containing suitable 
chemical reagents, which will generate pro- 
portionate and appropriate electrical impulses 




smelling* a civet cat across tteworW 



when exposed to vapors, essences, gases, or 
finely divided particles suspended in air; and 
the rest is a cinch. When that dingus is 
invented and anything can be developed if 
the Board of Directors will appropriate enough 
money we shall be able to smell a civet cat or 
a piece of frontage de brie across the world. 
Oh, but that will be a glad day! 

When will it dawn? No one who has given 
due heed to the human mania for invention can 
doubt that it will arrive. But when? Not 
immediately. For those who insist on figures, 
I am glad to estimate that its chances of 
arriving within the present century are only 
314 in 1,000,000,000,000,000,000,000,000,000. 
Our readers will recognize this proportion 
immediately as being of about the same order 
of magnitude as the probability of M. Leon 
Trotzky voyaging to the United States to 
address Congress and to become a master of 
boy scouts. 

The second portion of this learned treatise 
occurred to me while I was engaged in some 
research work of a medical nature. It appears 
that when a man dies the senses usually fail 
in the following order: smell and taste, sight, 
touch, and hearing. The significance of this 
to broadcast listeners is obvious, In the 
physiological turmoil of dissolution,, when the 
individual is no longer responsive to odors, 
tastes, spectacles, and contacts, he can still 
harken to his favorite broadcasting station. 
He can hear that, more or less, until he blows 
up entirely. There is an assurance which 
should destroy the fear of death! If any 
patron of broadcasting wishes, in gratitude, 
to send me a check for $10,000, my address 
may be obtained from the Editors. 



ON 



"BIRTHDAY 



WITH this number, RADIO 
BROADCAST is three years old 
and we are going to take this 
opportunity of climbing to the 
house top and shouting about ourselves. 
During the remainder of the year, we will 
be modest and hide our light under a 
bushel, but on our birthday we should 
have a bit more latitude. 

We feel that we are doing the job that 
we set out to do pretty well. If this pre- 
sumption is unwarranted, we invite you to 
tell us wherein we have failed in order 
that we may not appear to fail again. Our 
job is not an easy one and we're human 
just like you, and we not only can, but 
sometimes do make mistakes. As a rule 
our mistakes are brought home to us in 
no uncertain terms, but there may be a 
few we've made that you haven't told us 
about. 

DURING the last three years we have 
been plugging along with ideals, 
which, for a while, seemed like the pot of 
gold at the rainbow's end. These ideals 
are approaching nearer to actuality all 
the time. Our first and perhaps most 
important ideal from your point of view is 
a desire to present to our readers the best 
technical information that.research makes 
available. It is with considerable pride 
that we recall having published the first 
article on a transformer-coupled super- 
heterodyne, and another article describing 
various important experiments with the 
"super." It is significant to note that 
literally hundreds of "supers" have been 
described by other publications and that 
we find our first set for home construction 
is just about as good as any of the newer 
types with the single exception of the 
Hanscom super-heterodyne, and that re- 
ceiver saw the light of day in our own pages. 
There are other circuits we have des- 
cribed in the magazine during our short 
three years of publication. The Knockout 
series of receivers have been tremendously 
well received by readers of the magazine 
in practically every part of the world, and 
if the letters which you, the reader, write 
us, can be accepted as any indication, that 
series is becoming increasingly popu- 
lar. And these receivers are popular, fX 
we feel, because they fill a very definite V 



want among radio constructors. Our cri- 
terion is " Such a receiver and circuit must 
be reliable and technically sound. It must 
be helpful and useful to the radio construc- 
tor." These requirements, we feel, our 
construction articles have fulfilled. 

And while we're on the subject of cir- 
cuits, it is in order to say a word about 
our attitude toward "trick circuits." 
We never have and never will publish any 
construction articles on trick circuits. 
Our ideal is the publication of one ex- 
tremely good "how to make it" article a 
month. If it employs a new, but good 
circuit such as the two-tube super- 
heterodyne we have up our sleeves for 
next month so much the better. If on 
the other hand, no really new circuit is 
found, a more satisfactory arrangement 
of an old but good one is, as a rule, of real 
value. In March of last year we published 
an article entitled "The Truth About 
Trick Circuits." One gentleman whose 
circuit was rather severely criticized in the 
article brought suit against us in court 
for $100,000 damages. Fortunately for 
you and for us, the jury decided in our 
favor. We shall continue our policy of 
telling the truth, even when it hurts. 

AS A parting shot, we cannot resist 
mentioning the International Radio 
Broadcast Tests which were conducted 
by us for the second time last November. 
To you we owe a vote of thanks for your 
cooperation in making them a success. 
And they were more successful than any- 
thing of the kind ever attempted. From 
last year's experience we have learned 
much which will make our work of prep- 
aration for next fall much more effective. 
Everything considered, we have had a 
fairly good and profitable time together 
during our short friendship, and our plans 
for the immediate future will, we trust, 
meet with your entire approval. As an 
example of some of our plans, we are glad 
to announce that we are going to add eight 
pages of text beginning with the June 
magazine. We greatly appreciate your 
friendly support and trust that our efforts 
in the future will warrant its continuance. 





New Fashions in Radio Programs 

How the Present Trend of Radio Advertising Is Improving the Quality of 
Broadcast Programs A New and More Intelligent Role for the Announcer 
What the "Balanced Performance" Means to the Radio Listener 

BY JAMES C. YOUNG 



AY BODY who has listened-in on the 
radio knows that weary feeling which 
sometimes steals upon the heart when 
the announcer reaches the next num- 
ber. As for the announcer, he is a man wor- 
thy of kindly thoughts. He must go through 
365 nights in the year, announcing anything 
up to a dozen numbers every night. And 
he must endeavor to introduce each one in 
an original way. 

Some announcers are businesslike and crisp. 
They stick to their subject. Others affect 
the grand manner and cultivate theatrical 
inflections of the voice. Some others alas! 
turn to humor. That is the most painful 
method in the end. But whatever the method, 
the announcer has one 
of the hardest jobs in 
the radio business. 
He strives to make 
himself interesting 
every evening, and he 
must attempt the 
thing with the same 
old tools. We know 
in advance, every 
trick that he can play 
yet we must listen 
and hope for the best. 
Only a brave man 
would apply for the 
job. There should be 
a certain award in 
paradise for every 
announcer. 

Of all the announc- 
ers known to the ra- 
dio public, the noted 
"Roxie" has gained 
the surest hold on 
popular favor. His 
methods .are dis- 
tinctly personal and 
highly successful. He 
is the leading man 
of his own program 
and probably known 



So This Is Advertising! 

For some time, radio listeners in the east- 
ern and central parts of the United States 
have listened faithfully every Tuesday night 
at nine to the entertainment given during 
what was called the Eveready Hour. These 
programs have differed from the usual run 
of radio entertainment, for they have been 
presented as a complete unit. And they 
have been well done. The idea of making a 
radio program follow one plan or idea for 
several hours at a time is not new WGY and 
others have used it in the radio play, and 
wjz made some sporadic efforts along this 
line with their "Spanish Night" and others. 
Radio broadcasting is nothing more or less 
than good showmanship, and as Mr. Young 
points out, we cannot expect the announcer 
to do constant marvels with an old bag of 
tricks. The step in broadcast programs 
which the author describes so interestingly 
is a real forward and important one, we be- 
lieve. One frequently hears the fear ex- 
pressed that broadcast programs will even- 
tually turn into nothing but constant and 
very insidious advertising, but it is our opin- 
ion that the natural adjustment of things 
will prevent the overloading of the air with 
advertising that is objectionable. THE 
EDITOR 



to a larger number of followers than any other 
personality associated with radio. 

Interesting things happened when the men 
higher up at WEAF undertook to edit " Roxie's" 
little monologues. For some time WEAF has 
believed that the endless repetition of announce- 
ments was trying on radio nerves. And WEAF 
suspected that "Roxie's" monologues were 
somewhat trying as well. Therefore the blue 
pencil went into his talk about the old folk 
back home and the condition of Aunt Ma- 
tilda's health. 

On one eventful Sunday night several 
months ago "Roxie" out-did the most stilted 
introduction known to radio. A host of fol- 
lowers listened and wondered and became 
amazed. What was 
the matter with 
"Roxie"? Next day 
the papers told them. 
He had been edited. 
Immediately an al- 
most unanimous pro- 
test poured in upon 
WEAF, the greatest 
expression of opinion 
ever drawn from a ra- 
dio audience. There 
was plenty of static 
in that protest. It 
spluttered a good 
deal, demanding that 
the editorial frown 
be removed from 
"Roxie's" copy. And 
WEAF relented, with- 
out even putting an 
ear to the ground. 
Such is the public 
estimate of one an- 
nouncer who has 
caught the popular 
favor. But he is al- 
most alone among a 
multitude. For some 
time it has been evi- 
dent that radio must 



84 



Radio Broadcast 



evolve a better method of presentation for its 
programs. 

It was this kind of reasoning that led to one 
of the distinct innovations in radio, a dramatic 
program presenting music and theme in a form 
of continuity which holds many possibilities. 
When radio was new somebody perceived the 
need of a cue to what the programs meant, 
and that brought in the announcer, of whom 
great things were required. He .has met 
the task well, but the continuous program, 
built in dramatic sequence, will make his 
work considerably easier for himself and the 
listener. 

Instead of bobbing up every ten minutes, 
like those in a class, he can make one an- 
nouncement in an hour and try to do it in 
a humanly interesting fashion. No tricks are 
required, just a plain statement of what 
should be a few pertinent facts. Then the 
continuing theme must keep alive the interest 
created, constantly reminding the listener of 
the general trend, but steadily developing the 
performance as it is done in the theater, on 
the screen everywhere the drama has an in- 
fluence. This, in fact, is the true radio drama 
and not a hybrid adaptation such as the read- 
ing of a play. Radio has developed every 
means of expression peculiar to itself and it is 
thoroughly reasonable to suppose that its own 
kind of drama will be the next step in evolu- 
tion. 

That stage is now opening before us, if we % 
may believe the evidence furnished by one 
successful broadcaster, responsible for . the 
performance known to a national radio aud- 
ience as the Eveready Hour. Promptly at 
nine o'clock each Tuesday night the enter- 
tainers in this group take over the air as con- 
trolled by WEAF in New York. For the next 
hour, some millions of Americans are enter- 
tained in a way distinctly new to radio. 
WEAF transmits the program to ten other 
stations, WFI, WCAE, WGR, WEEI, WEAR, wcco, 
wwj, woe, WSAI, and WJAR. And for sixty 
intensive minutes an invisible audience equal 
to the population of many nations may enjoy 
a real radio drama. 

SOMETHING GOOD DOING EVERY MINUTE 

HOW is the thing done? The answer to 
that question goes back a little way. 
The first attempt grew from an acute sense of 
the elements lacking in a typical program, 
which too often has reached the point where 
the old minstrel show wound up. No matter 
how clever Mr. Bones might be, it was not 
possible for him to continue longer than he did. 



And the announcer in a large measure corres- 
ponds to Mr. Bones. He is supposed to say 
something clever whenever the show lags. 

The Armistice Day program of last year for 
the Eveready Hour was a notable example of 
what can be done to brighten a radio perform- 
ance. The announcer made known in an 
easy, conversational way that his listeners 
were to think of themselves as the men inside 
"a sleeping stretch of tents, thousands of men 
at their rest. The sun has just risen; the 
guard has raised the flag and our slumbers are 
broken by reveille, 'Oh, How 1 Hate to Get 
Up in the Morning.'" 

Here was a bit of rapid fire psychology at 
its quickest. The listener instinctively 
handed over his imagination to the entertainers 
and let them do with it just about as they 
pleased. This quality of imagination ac- 
counts for a fair half of the success which 
attends any program. And this is the way 
the entertainers proceeded, a quick succession 
of voices : 

Sergeant: "Fall in! 'Ten-shun! Right 
Dress! Front Count off." 

Then the other voices came into play in a 
way familiar to a large number of listeners: 

"1234 1234", 

. . . Sir, the company is formed." 

Any man ever in the army, or whoever had 
a friend in the ranks, or who even knew any- 
thing about the war, must be beguiled by that 
kind of introduction. -Then the Captain 
speaks: 

"Sergeant, after mess march the company 
to the Y hut. There will not be any drill this 
morning. The Eveready entertainers have 
come to camp and they will put on a show 
this morning. That's all, sergeant." 

This was getting over the difficult business 
of introduction in a way to please and charm 
and not once to jar the senses. Next came the 
assembled voices in the supposed Y hut, evok- 
ing memories of 1917, when the world seemed 
as if it might be going to pot. After a period of 
singing, the announcer speaks again, but he 
has become a monologist by this time and we 
feel friendly toward him instead of wishing 
that he would get through once and for all and 
keep quiet. This is what he says: 

"We've come to the day when tin hats have 
been issued and the boys are laying bets 
that they will sail soon. They win. We're 
on the transport. There isn't much noise 
permitted as the big hulk creeps out of Ho- 
boken in the blackness of early morning, but 
many of the uniformed passengers feel like 
singing." And they do sing, just about what- 



New Fashions in Radio Programs 



ever they like- "Good Bye, Broadway," 
"Over There," and "'Till We Meet Again." 

If a listener could resist a tug at the heart 
when that last song died out he would be a 
strange sort of American. But it has not been 
recorded that anybody failed to keep spiritual 
company with the transport on its eventful 
way. Then comes France: danger, war, and 
death. At the end, "Flanders Fields" is 
declaimed to music, and taps sounded. 

UNITY AND INTEREST FOR THE PERFORMANCE 

THAT is an excellent example of the con- 
tinuous dramatic performance by radio. 
It is the same kind of vehicle that once was 
used to carry along the old variety show when 
it began to emerge from a number of disjointed 
acts, which afterward became vaudeville. 
Although vaudeville is a reversion, in a meas- 
ure, it is a performance requiring no interpre- 
tation by announcement. Even the boy who 
used to come out and change the signs has 
disappeared, and now an electrical device 
supplies the information that the next act 
will be the performing seals. 

Although radio has not offered us the seals 
as yet at least, not under that description 
there is a wide field of development possible 
by the adoption of the continuous theme. 
The idea was not wholly original with the 
group of entertainers who have scored so 



successfully by this means, but they at least 
have utilized it with more definitely successful 
results than any other group. Therefore they 
must receive recognition for their efforts, 
along with the men in charge. 

There is virtually no limitation on what may 
be done with the dramatic theme by radio. 
Another of the Eveready Hours was devoted 
to a performance described as the Age of Man 
program. This choice arose from the wish to 
present a program of old songs in a new way, 
attempting to escape from the boresome device 
of an announcer with trembling voice who 
talked about the days down on the farm. 
That sort of introduction is particularly bad 
when the announcer speaks about a farm with 
all the intimate acquaintance of a native New 
Yorker. In this case the introduction was 
managed to the accompaniment of a piano and 
violin playing a lullaby, which swiftly devel- 
oped into " Rock-a-Bye, Baby." 

CLEVER THEATRICAL MECHANICS 

IT IS not an easy matter to prepare the mind 
of a radio audience in something like two 
minutes for such a song as "Rock-a-Bye, 
Baby." Everybody in America has heard 
that lullaby so often at all stages of life, that 
it must be particularly well rendered to hold 
the attention. It cannot be literally thrown 
at an audience, as so many songs are tossed 




MEMBERS OF THE RADIO ENTERTAINERS 

Grouped during a typical Eveready Hour. They are: Left to right, seated: Charles Harrison, tenor; Beulah 
Young, soprano; Rose Bryant, contralto; Wilfred Glenn, baritone; all of the Eveready Mixed Quartet; stand- 
ing beside Mr. Harrison, Graham McNamee, announcer; standing behind Mr. Harrison, A. J. Klein, noted 
African hunter; standing to Mr. Glenn's right Edward Berge, pianist; Alex Hackel, violinist, and Jacque de 
Pool, cellist, of the Eveready Trio. Others are chorus singers selected from the New York Oratorio Society 

and extra orchestral players 



86 



Radio Broadcast 



through the ether. "Rock-a-Bye, Baby" re- 
quires gentle treatment and a sympathetic 
mood. 

Well, this particular evening of old songs 
was pronounced one of the biggest things 
done in radio entertaining for months. A re- 
sponse from far and near showed that the 
program landed in the psychological center 
of the public favor. This program progressed 
from its opening number with such music as 
Brahm's "Cra- 
dle Song," grad- 
ually advancing 
through the 
songs of boy- 
hood, youth, 
and the court- 
ing age. Then 
the songs went 
on to the suc- 
ceeding stages 
of life and what 
obviously must 
be the last 
Home, Sweet 
Home. 

Still another 
successful pro- 
gram was made 
up of sea songs, 
a class of musi- 
cal composi- 
tion especially 
suited for radio 
because of the 
long lilt to the 
melodies, which 
seem to slip 
onto the ethe- 
real waves with 
a genius all their 
own. A depar- 
ture still further 

afield brought before the microphone one Mar- 
tin Christiansen, able seaman turned taxi driver. 
And the announcer made known that Christian- 
sen literally was going to tell "the story of his 
life." Of course, he did not express the matter 
just that way. Instead, he explained that some 
time before/ Christiansen was sitting on the 
box of his cab in New York, reading a morning 
paper, when he chanced to see in the news 
that William Beebe was homeward bound 
from the Galapagos Islands, one of the lost 
places of the Pacific. 

Christiansen read that item and rushed 
down to the dock so that he might greet the 
only man he had ever heard about who knew 




RED CHRISTIANSEN 

The "sea-going" taxi driver of New York whose adventures in the 
lost islands of the Pacific were seized upon as material for one pre- 
sentation of a new type of radio program 



those islands. Christiansen was on the dock 
when the explorer arrived and the story he 
told Beebe afterward constituted a rattling 
good chapter in the explorer's book about 
those islands. All of that explanation was 
packed into a few sentences by the announcer, 
who then turned over the air to Christiansen, 
and let him speak for himself. He was the 
sort of man fully capable of that effort and 
proceeded along this line: 

SOMETHING DE- 
CIDEDLY NEW 

W ELL > l 

suppose 
the story begins 
when I signed 
up with the 
bark Alexander, 
down on the 
other side of the 
world. That 
was at New- 
castle, New 
South Wales, in 
Australia. The 
Alexander was 
loaded with a 
cargo of coal 
bound east- 
ward across the 
Pacific for Pa- 
nama. She car- 
ried a captain, 
mate, cook, 
and sixteen of 
us men." 

Now almost 
every boy in 
the world has 
wanted to be a 
sailor and prac- 
tically every girl 

has feared that her first sweetheart would run 
away, as he threatened, because she refused his 
manly hand. The appeal of the sea is universal. 
It is probable that no other class of fiction ever 
written is read by so many people. If Chris- 
tiansen's introduction of his story had ap- 
peared upon the printed page, instinctively we 
would have moved a little closer to the light 
and have settled down for an evening's joy. 

That is what happened with the radio 
audience. Who can imagine a man telling us 
about sailing on a trip like that, without every 
poor landlubber lending eager ear? Chris- 
tiansen was better than a passable story teller. 
He went on in this strain: 




SCENES IN THE GALAPAGOS ISLANDS 

Often called the lost islands of the Pacific, which \\illiam Beebe, the noted explorer and scientist, 
investigated some years ago. A taxi driver in New York, who had been a sailor shipwrecked on the islands 
appeared on a radio program and described his experiences there. Broadcasting programs of a high order are 
tending toward better unity and the " Explorer's Night Program" in which Mr. Christiansen took part from 
WEAF and connected stations was one of this new type. The center cut shows a giant marine lizard which 
exists only in the Galapagos Islands. It lives in the sea and is about five feet long. The upper left picture 
shows specimens from the sea being gathered from the yard-arm of the exploring ship. The upper right 
photograph shows a huge boa constrictor caught near the Islands. The lower left picture is of a giant 
marine lizard feeding in the surf. The lower right shows a Hoatzin fledgling, the missing link between the 

lizard and the bird 



Radio Broadcast 



" I had been living in a sailor's boarding 
house, run by Nellie Simonds. The day we 
shipped, Nellie rowed out in the bay and 
brought some refreshments along as a parting 
gift. I don't mind telling you that her brand 
of refreshments made a bigger hit with us than 
the stuff we had to drink before we got through 
that voyage. As the tug took hold and started 
off, we sang to her and she sang back. It was 
a happy send-off." 

That immediately opened the way for the 
quartette to sing one of those good-bye songs, 
and the quartette performed in fine fettle. 
Then Christiansen went on again. Before he 
stopped talking, there was hardly a radio ear 
in some thousands of miles that was not 
aquiver with his story about those forsaken 
islands and the things that happened there. 
It was such a yarn as Stevenson would have 



liked to spin. A listener could experience for 
himself all the heartache, thirst, and peril that 
went into the sailor's adventures. In the end, 
it was pleasant to know that he had adopted 
the comparitively easy and safe pursuit of driv- 
ing a New York taxicab, although many men 
of a less eventful past might call that high 
adventure. 

The Christiansen story was a new endeavor 
in many ways, and received wide recognition 
from the press. 

THIS IS ADVERTISING 

WHO would ever undertake, let us say, 
to link the yarn of a sailor's adventures 
with advertising? And the Eveready Hour 
entertainers, of course, represent the idea of 
selling by publicity. Here is a development 
so broad that the possibilities cannot be even 




EXCELLENT CLASSICAL MUSIC 

Is given during the Eveready Hour by the Mixed Quartette, which consists of Wilfred Glenn (left), baritone; 
Rose Bryant, contralto; Beulah Young, soprano; Charles Harrison, tenor, Tom Grisselle. During the 
specially arranged hour of entertainment, given each week by this organization, each is a complete entity. 
The program by this group and others of the organization is part of a completely balanced program which has 

been well received by the listeners 



New Fashions in Radio Programs 



89 



estimated. We may conceive of a new expe- 
dition to the pole so that the explorer shall 
describe to us how comfortable he was in some 
particular brand of knit underwear, while he 
drank a special blend of tea and munched upon 
a soda cracker of national reputation. 

Whatever are the developments in store 
for us, the established fact is that a sailor's 
tale of perilous deeds in far places makes 
mighty interesting material for a radio pro- 
gram. This is a far step from the day not 
long past when the only kind of discourse 
known to radio was the sort which dealt with 
the advisability of accumulating enough for 
old age by smoking one cigar less every day. 
Nobody will fall out with the wisdom of that 
discourse, but it hardly was entertainment. 
There has been no perceptible diminution in 
the consumption of cigars nor any appreciable 
gain in the total of savings from the thousands of 
such lectures forced upon the ear of the nation. 

But if we know the human heart at all, we 
cannot doubt that Christiansen's yarn will be 
talked about around uncounted firesides for 
many months. It was the kind of tale to 
make everybody huddle closer to the hickory 
log or even the radiator and bless their 
stars that those islands with the terrible name 
are so far away. By association, those who 
heard the story at first hand will long think of 
it as a part of the Eveready Hour program. 
And the programs just as inevitably are asso- 
ciated with national 'advertising of the wares 
behind them. 

Such considerations lead naturally to the 
oft discussed problem of where advertising 
legitimately stops or begins in radio broad- 
casting. Whatever the ethics of the case, 
it is beyond dispute that radio advertising has 
increased greatly within recent months. It 
is in a fair way to equal the power of the 
accepted advertising in newspapers and mag- 
azines. So far it usually has taken the in- 
direct form. But the appeal is none the less 
direct, we may be assured by the large number 
of concerns turning to this method. 



At a moment when the country is enjoying 
a broad prosperity, radio advertising would 
seem to have entered upon a period of develop- 
ment that will surpass anything ever known. 
The experiences of the automobile industry 
and the movies are being repeated anew. All 
of these considerations may or may not in- 
terest the radio user. What he seems to care 
about principally is the quality of entertain- 
ment offered for his amusement. Certainly 
that quality grows better every day and the 
element of originality introduced by the enter- 
tainers ' in question, under the immediate 
direction of Paul F. Stacy, suggests a means 
of enlivening the radio program for the benefit 
of everybody. 

The day evidently is not far removed when 
the typical radio program will cease being its 
present jumble of odds and, ends put together 
on the general pattern of Joseph's coat. We 
may expect a balanced performance, to use a 
theatrical term, and it is not improbable that 
an entire evening's entertainment will be pre- 
sented by the medium outlined. It should be 
possible to arrange such a program so as to 
encompass a wide variety and still preserve 
the theme of continuity. . A theatrical setting 
of the kind suggested on the transport and the 
canteen would be easily adaptable to lengthy 
performances. One of the first dramatic 
principles holds that the continuity of time, 
place, and action best assures command of 
attention. 

Whether this development be great or small, 
the radio audience of America at least may be 
thankful to the Everyeady Hour entertainers 
for introducing a device to help out the hard 
working announcer. Poor fellow, he has 
labored nobly, turning phrases around, trying 
to be humorous and grave, and otherwise 
experimenting with the tools in his kit. : Al- 
though there may be nothing distinctly new 
beneath the sun, it is certain that the con- 
tinuous dramatic theme for radio programs is 
a decidedly fresh and pleasant departure "on 
the air." 



:..- ...... 

GUGLIELMO M ARGON I has written an artic-le for RADIO BROADCAST 
which will appear in an early number. He writes, of his : recent experi-'^' 
ments, in England, at sea, and aboard his yacht, with radio transmission by His 
famous "beam system". Signor Marconi firmly believes that beam transmission 
of radio energy on very short wavelengths is a general development that is now 
upon us. This article is the first that Signor Marconi has published in America 
describing what he believes is a revolution in radio transmission. 



Do Weather Conditions Influence 

Radio? 

A New Theory, Advanced by a Climatologist, Tending 
to Prove That Atmospheric "Highs" and "Lows" and 
Other Weather Phenomena Affect Receiving Conditions 

BY EUGENE VAN CLEEF 



Ohio State University 



IT IS certainly not uncommon to hear radio 
enthusiasts say, " I couldn't get much last 
night, too much static," or "Bad night 
last night, couldn't get a thing from the 
west and just a few eastern stations," or again, 
"Can't expect results to-night, too rainy." 
Correct as the reports 
may be as far as ac- 
tual poor reception is 
concerned, the diag- 
noses are not always 
true. This is because 
the average person is 
unacquainted with 
the mechanics of the 
circulation of the 
atmosphere. He 
knows that the 
weather changes, but 
does not appreciate 
fully the direction of 
these changes and the 
part which atmos- 
pheric pressure plays 
in our daily weather. 

Weather, of course, 
is local at any given 
time. One could well 
say that weather 
travels, and the 
weather which a given 
city west of us has 
to-day, may be the 
kind of weather we 
shall have within the 
next twenty-four to 
thirty-six hours. This 
suggests that a certain 

brand of weather is not universal at a given 
time of day or night, but that there may be 
a radical difference in the state of the weather 
at the broadcasting station and that where the 
receiving instrument is located. 

The weather in the United States changes 



Talk Minus Facts 

T"*HQSE interested in radio have for years 
* tried to find out the factors which in- 
fluence the radiation and reception of radio 
waves. There have been a number of theories 
adduced to explain the sometimes peculiar 
variation of the signals. Probably best 
known of such theories is the Heaviside layer 
theory, which, very briefly, assumes that the 
various ionized layers of the upper atmos- 
phere refract, absorb, or aid the waves in their 
passage. RADIOBROADCAST does not assume 
responsibility for Mr. Van Cleef's conclusions 
that weather conditions definitely affect radio 
conditions, but we should like to observe that 
his findings seem to fit in very well with what 
actually is the case. It is quite possible that 
atmospheric conditions have a definite and 
yet unexplained relation to the variations in 
the Heaviside layer. It may be, too, that 
the findings of this experimenter can be put 
with the conclusions of other experimenters 
and relations between phenomena as yet un- 
known may be seen. At least, the author 
has done a genuinely good piece of work. 
Those who have similar access to national 
weather information should be very much 
interested in continuing and checking these 
conclusions. THE EDITOR 



because of the influence of shifting atmospheric 
pressure areas known technically as Cyclones 
and Anti-Cyclones. In the cyclone, the air in 
general blows spirally inward, upward, and 
in counter-clockwise fashion. In the anti- 
cyclone, the air blows spirally downward, 
outward, and in a 
clockwise direction. 
In neither pressure 
area is the movement 
violent. The dia- 
meters of the storms 
may be anywhere 
from 400 to i 500 
miles. These pressure 
areas are not always 
symmetrical in form 
and consequently 
their diameters may 
vary along a dozen 
different radii. 

These storms travel 
across the United 
States in a general 
easterly direction, en- 
tering the United 
States either from the 
southwest, west, or 
northwest and leav- 
ing by way of the 
Atlantic coast, but 
most often by the St. 
Lawrence river val- 
ley. In the autumn 
months, September 
to November, hurri- 
canes and violent 
cyclones, may enter 

the United States from the southeast in the 
vicinity of Florida, penetrate at times' as far 
as the Galveston coast of the Gulf of Mexico, 
and then following the customary paths 
across the eastern half of the country. The 
hurricane is the exception and not the rule. 



Do Weather Conditions Influence Radio? 



CYCLONES and anti-cyclones pass across 
V-* the country approximately every three 
to four days, varying in frequency with the 
season of the year. They always occur alter- 
nately. Two high pressure areas (anti- 
cyclones) or two low pressure areas (cyclones) 
never succeed each other. "Lows" and 
"Highs," as they are named on the weather 
map, always alternate. Meteorologists have 
studied the variety of weather associated with 
these pressure centers, and through the agency 
of the United States Weather Bureau, the 
forecasting of the passing weather has attained 
a fair degree of accuracy. 

In general, it may be said, that cloudy, 
rainy, or snowy weather and moderate to high 
temperatures are the accompaniment of Lows, 
while clear and cool to very cold weather 
accompanies Highs. There are exceptions to 
both of these assertions, but they are not 
many. Now, a striking feature of these 
pressure areas lies in the variation of their 
respective intensities as revealed by the 
arrangement of their Isobars. An isobar is a 



line which passes through all points having the 
same atmospheric pressure, i.e., through all 
points where the barometer reads the same. 
The isobars tend toward a concentric arrange- 
ment. In an ideal pressure center they would 
be absolutely concentric. Irregularities in 
their course may be due to many reasons, such 
as temperature differences, variations in mois- 
ture content of the air, topography, and so on. 

DO WEATHER CONDITIONS INFLUENCE RADIO 
RECEPTION? 

IT OCCURRED to the writer when he 
1 heard statements referring to the weather 
and radio reception, such as are quoted at the 
beginning of this discussion, that their logic 
was frequently faulty. It seemed that with 
broadcasting and receiving stations often- 
times 500 to 1000 miles apart, the local 
weather conditions at the receiving station 
could not have much influence on reception, 
unless the same conditions prevailed over all 
the country between the two stations. Such 
uniformity in weather is not common. There- 
fore, to ascribe poor receptivity to the local 
weather could not be an accurate analysis. 
Furthermore, it was true that occasionally 



ment of Agriculture 
DAILY WEATHER 



OTES 

, 76th meridian time. 
Air pressure reduced to vea level 
ISOBARS, (continuous lines) paas through points of 

ERMS (dotted lines) pass through point* of 

equal temperature; drawn for every 10* 
Symbols indicate state of weather O clear 9 partly cloudy 
cloudy rain snow report missing 
Arrows fly with the wind. 
SHADED AREA shows precipitation of 0.01 inchor 

more during last 24 hours 
Wind Velocities of less than 10 miles an hour, and amounu 

of precipitation of less than 0.01 inch, are not published 




A TYPICAL WEATHER MAP OF THE UNITED STATES 

Which shows clearly the alternating "Highs" and "Lows." According to the theory advanced by the 
author, radio reception in a low pressure area tends to be somewhat weaker than in a high pressure zone of 

corresponding intensity 



Radio Broadcast 



when the weather was "bad," reception was 
good, although the association of the two facts 
at such times was entirely overlooked. It 
seems to be a common trait among most of us 
to analyze and criticise rather thoroughly 
when things go wrong but to take matters for 
granted when we are enjoying results which 
seem to us to be wholly normal. 

The situation just noted led to an investi- 
gation, which has thus far revealed some strik- 
ing conclusions. ;lt seems that since broad- 
casting involves the transmission of electro- 
magnetic waves, a wave motion transverse 
in ;type, there might be a definite relation 
between such transmission and the circulation 
of air in High and Low pressures. Obser- 
vations were made to determine whether any 
su^h relationship might exist, or whether there 
could be a relation between the strength and 
clarity of reception, and the arrangement of 
isobars. 

NEW THEORIES FOR RADIO CONDITIONS 

AFlVE-tube neutrodyne set was used, with 
an outside antenna about 125 feet long, 
and about 30 feet. from the ground. The 



direction of the antenna was almost exact- 
ly northeast-southwest. The observations 
follow: 

1. If a line connecting the receiving station with 
the broadcasting station crosses the interven- 
ing isobars at right angles, reception is at its 
best. 

2. The steeper the isobaric gradient (that is, the 
closer the isobars to each other) the stronger 
the reception. 

3. The more nearly the transmitted waves ap- 
proach parallelism with the isobars, the weaker 
the reception. Under these conditions, fading 
occurs. 

4. Reception in a Low pressure area tends to be 
somewhat weaker than in a High of correspond- 
ing intensity. 

5. Reception is weaker when the transmitted 
waves cross from one pressure area into another 
than when they travel only within one area. 

6. The strength of reception for any station is a 
factor of both its location within a pressure area 
and its position with respect to the broadcast- 
ing station. 

7. "Bad weather" does not affect reception, ex- 
cepting as it may be the index of an unfavor- 
able pressure distribution. 




AN IDEAL WEATHER MAP 

Drawn to show the relation of the strength and clarity of reception to the angle between the direction of 

transmission and the isobars. An isobar is a line which passes through all points whose barometric pressure 

is the same. The arrows on the map indicate the direction from which broadcast signals were received during 

one of the tests made at the author's station in Columbus, Ohio 



Do Weather Conditions Influence Radio? 



93 



8. Reception can be as good in "bad weather" 
as in good weather if the pressure distribution 
is right. 

9. Temperature does not influence reception, 
excepting as it may be the index of pressure 
distribution as follows: 

(a) Reception is better in winter than in 
summer because the cyclones and anti- 
cyclones are more intense in the winter 
period. 

(b) Reception is better when temperatures 
are low than when high, because low 
temperatures usually indicate intensive 
High pressure areas, that is, areas with 
steep isobaric gradients. 

(c) Low temperatures accompanying poorly 
defined High pressure areas make re- 
ception poor. 

10. Shallow or flat pressure areas result in much 
static-noise in the receiver. 

HOW CONDITIONS CAN BE FORECAST 

WITH the above observations well de- 
fined, the question which quite natur- 
ally arises is, Can the strength and clarity of 
reception be forecast? The answer is, "Yes!" 
It can be forecast with the same degree of 
accuracy as the weather, but hardly with any 
greater degree. Forecasting the weather de- 
pends upon a knowledge of the movements of 
cyclones and anti-cyclones and their peculiari- 
ties in various seasons of the year. Forecast- 
ing radio reception, assuming no interference 





Underwood & Underwood 
WEATHER FORECASTING APPARATUS 



According to the results of the experiments of the author, when weather 
conditions are accurately known and compared with radio transmission 
and reception phenomena, it is probable that much may be discovered 
about the mysteries of freak radio signals. The device shown in the 
photograph records the direction and velocity of the wind 



Underwood & Underwood 
THE NETHOSCOPE 

Used by the Weather Bureau to aid in predicting the 

weather. Simplified, the apparatus is a black 

mirror and is used to determine the direction and 

velocity of clouds 



by regenerative sets or the like, is dependent 
likewise upon a knowledge of the movements 
of the same pressure areas. However it in- 
volves not the forecast- 
ing of the probable state 
of the weather at the 
station concerned, but 
only the prognostication 
of the arrangement of 
the isobars between the 
respective receiving and 
broadcasting stations, and 
the probable steepness of 
the isobaric gradients. 

By such forecasts, much 
may be saved to the 
people. One may know 
the futility of trying to 
get certain stations on 
given nights and save 
power, time and nervous 
energy. Sets may not be 
blamed for poor service 
when pressure conditions 
are the cause; and broad- 
casters may not be 
criticised for failure to 
speak plainly or loudly 
enough, or in general be- 
cause of lack of efficiency, 



94 



Radio Broadcast 



when as a matter of fact they are performing 
properly and well. 

Another phase to this problem, not yet 
worked out, involves the relation between the 
power required to send the waves and a 
possible adjustment with respect to the 
atmospheric pressure. We know there is 
some relation to sunshine, for during the 



daytime one can not receive over great dis- 
tances, unless the sky is clouded the entire 
distance. So there may be a correspondence 
between the wave motion itself and the air 
pressure, which if learned, would reduce the 
amount of power required for wave trans- 
mission and perhaps in still other ways wholly 
revolutionize broadcasting. 



how DO 

vou 

KNOW I o 
CALIFORM/A, 




OBSERVATIONS ON THE RADIO LIFE.' NO. 2 

California on the loud speaker 




PRIMARILY the star of approval, which appears in RADIO 
BROADCAST advertising, means "Approved by Radio Broadcast 
Laboratory." Although this certification means a great deal 
to those advertisers whose copy bears this mark of approval, it 
does not necessarily discriminate against the copy not so marked. 

In placing this sign of approval in our advertising pages, several 
issues are considered. It is far from humanly possible for us to test 
each item advertised by every manufacturer and still do the great 
amount of development work which has proved so valuable to our read- 
ers. Where we have sufficient knowledge of a manufacturer's products 
and his business standing, we place our Star on his copy with the assur- 
ance that, if the customer is not satisfied, the manufacturer will refund 
his money. In case a manufacturer develops a questionable device we 
always request that samples be submitted for our inspection. Adver- 
tisers with whose products we are not thoroughly familiar are required 
to submit samples before receiving the Star. 

The meaning of the Star however, is not thus limited, for, added to 
the approval, which is advantageous to the manufacturers, we are not 
overlooking the prospective customers. A reader seeing the Star should 
not necessarily draw the inference that here is a product better than any 
other. It does, however, mean to the reader that he will either get 
satisfaction or his money back. In placing .the Star in advertising, we 
are assuring the reader of our confidence in these manufacturers. The 
omission of the Star indicates that we have not had the opportunity 
to become thoroughly familiar with the products advertised. The fact 
that advertising appears in our pages at all indicates that we consider 
it reliable. 

In placing our approval on apparatus submitted for test we have no 
intention of causing friction by unfair discrimination. Our approval 
does not in any way indicate that we assume that the products of those 
advertisers are perfect. What it does mean is that the manufacturer has 
satisfactorily met the claims he is making for such apparatus and that 
he supports his claims with a "money-back" guarantee. In passing 
on the apparatus in this manner, we must necessarily take its selling 
price into consideration and so the Star is an assurance that one will get 
full value on his investment. 

"Approved by Radio Broadcast Laboratory" gives the purchaser 
assurance that he is buying the product of a reliable manufacturer and 
that he can in this way feel certain of getting reasonably satisfactory 
results. Its purpose is to boost the legitimate and honest manufacturer. 
It is our intention to extend our present plans to the point where RADIO 
BROADCAST will carry no advertising where the apparatus has not ac- 
tually been tested in our laboratory. 



How to Solder 



BY WILLIAM F. CROSBY 



TO THE uninitiated, the art of solder- 
ing appears to be something which 
only the most expert workman can do. 
It appears to be a talent which the 
novice can hope to acquire only with years of 
practise. It may be an art, but it is an easy 
art, and one which even some of the most in- 
expert of our radio builders have conquered, 
to the great improvement of the sets they 
build. 

There is just one fundamental rule in suc- 
cessful soldering, and that is cleanliness. This 
does not necessarily mean that the man doing 
the work must have on a clean collar and his 
hands must be manicured; but it does mean 
that he must see that the soldering iron has a 
clean collar of solder and that the surfaces to 
be soldered are manicured. 

Seriously, though, soldering is easy, once the 
importance of having everything clean is 
realized. Solder will positively not stick to a 
surface which is oily or corroded. If one 
part is clean and the other dirty, the solder 
will stick to the clean surface but not to the 
dirty. If you do not believe this just try it 
and see. Fully half of those who have 
trouble with soldering because the surfaces 
will not stick, or the solder drops off, have not 
realized that a clean surface is the first essential. 




RADIO BROADCAST Photograph 
FIG. I 

The soldering iron should always be shinily clean. 
The burned coating which collects on the working 
surface of a gas iron can be removed with a flat file 
as shown in the photograph. When using the file, 
the solderer should push it away from him and lift 
the file from the surface on the return motion 



The next step is the consideration of the 
soldering iron itself. Many constructors are 
using gas heated irons with varying degrees 
of success, but once let a man use an electric 
soldering iron and he will never make further 
use of the gas range. These irons may be 
secured in many sizes and shapes and some of 
them have interchangeable points. With this 
type of iron it is possible to secure a fine point 
for small work, a curved point for the inac- 
cessible places or a blunt, heavy point for the 
work which is more in the open. The writer 
is of the opinion that the fine pointed iron is 
the best for all around radio work. It is 
satisfactory for coarse soldering and also for 
the finer work and if a little care is exercised 
in wiring the set, there is no reason why every 
connection cannot be reached. Of course the 
inside wires should be placed first and the 
work carried on so that the outermost wires 
come last. 

"TINNING" THE IRON 

f~^ ENERALLY a new soldering iron is not 
^-* "tinned." In other words the surface 
is coppery all over and, in passing, it might be 
just as well to point out that soldering "irons" 
are not iron at all but "copper," for it seems 
to conduct and hold the heat better. 

Now suppose we want to "tin" a new iron. 
The first thing to do, of course, is to get it hot, 
not red hot, and not cherry red either. Usu- 
ally a good test is to have a small can of solder- 
ing paste handy and dip the point of the iron 
in this from time to time. When the iron is 
sufficiently hot, the paste will sputter in a 
good lively fashion and after a little experience 
you will be able to tell at just what point the 
soldering is easiest. 

Assuming that the iron is properly heated 
the next step is to plunge the end briefly into 
the can of soldering paste. Before this is 
entirely burned off, solder should be applied to 
the end of the iron and then rubbed over the 
point with a soft rag. It is surprising to ob- 
serve the ease with which this is made to 
adhere, provided, of course, the point is 
clean. The whole end of the iron should be 
treated in this manner until it is tinned 
completely. Make sure that the rag is 
doubled back and forth several times so that 



How to Solder 



97 




KAURI BROADCAST 1'hotograph 

FIG. 2 

Rubbing the working top of the iron on a piece of 
sal ammoniac removes the oxide coating and pre- 
pares it for tinning. The iron must be quite hot 
and the surface of the sal ammoniac must be clean 



\ uur hand will not come into contact with the 
hot iron. This rag should be kept handy at 
all times and when doing extensive soldering, 
the point should be wiped clean occasionally. 
It may also be necessary to re-tin the point if 
the iron has become too hot at any time. 
When this is done, it is first necessary to scrape 
the point with a file so that the shiny copper 
is again exposed. The rest of the procedure is 
then followed as outlined before. 




RADIO BROADCAST Photograph 
FIG. 3 

Applying the strip solder to the cleaned tip of the 

iron. The solder should quickly take to the iron 

after it has been properly cleaned 



WHAT SOLDER TO USE 

'"THERE are many different kinds of solder 
* on the market, but it is generally con- 
ceded among radio men that good resin core 
solder is the best for all around work. This is 
excellent if used with a small amount of solder- 
ing paste and you can make up a joint which 
will last for years. 

Acid core solder is completely out of place 
as far as radio is concerned. The acid will 
attack the copper and cause quick corrosion 
with consequent noise in the set. Of course 
plain wire solder is excellent, but it will be 
necessary to use a little more paste with it. 

The paste consists of a resinous material 
of a pasty consistency which helps to make the 
solder stick by acting as a cleaning agent. 




RADIO BROADCAST Photograph 
FIG. 4 

A good soldering outfit. From left to right: liquid 

soldering flux, paste flux, flat nose pliers, electric 

iron, sal ammoniac, and strip solder 



There are many forms of this material some 
of which are liquid in form. It is never ad- 
visable to use too much of any of these ma- 
terials, because all of them will cause trouble 
if applied in this manner. 

The customary thing is to have a match 
handy, and with this dip out just a tiny bit 
of the paste and apply it to both surfaces to be 
soldered. A little solder is then applied to the 
end of the hot iron, the two surfaces placed to- 
gether, and the solder applied. Make sure that 
the surfaces are held tightly together until 
the solder has had a chance to cool. This is a 
matter of seconds only and before the joint 
becomes entirely cold, wipe it off with the rag 
used for cleaning the iron. This wiping off 
will remove surplus soldering paste or flux and 
prevent possible corrosion of the joint. 

Remember that a tiny drop of the solder 



98 



Radio Broadcast 




RADIO BROADCAST Photograph 



FIG. 5 

Wiping the iron to keep it bright. A clean iron 

means good work. Any old cloth may be used to 

wipe the iron 



will do the work better than a big crystal-like 
lump. The solder should be hot enough to 
flow evenly almost like water. The surface 
of a correctly soldered joint should be smooth 
with only enough solder to hold the joint to- 
gether. Wiping it off as suggested, will do 
much to improve the appearance. 

A PRACTICAL EXAMPLE OF A SOLDERING PROB- 
LEM 

LET us actually solder a joint. We will 
make a connection between a new piece 
of bus bar and an old soldering lug on a vari- 
able condenser. This condenser happens to 
be mounted on a panel in the usual manner. 

The first thing to do is to place the iron on 
to heat, either by plugging it in on the electric 
light socket or by placing it over the gas flame 
in the kitchen. While the iron is heating we 
get the rag, wire solder, and paste handy and 
then proceed to clean off the surfaces. The 
lug on the condenser is badly corroded and it 
will never hold solder. A small file or a bit of 
emery paper will help us here and the lug is 
soon shiny. It is also advisable to touch up 
the bus bar a little despite the fact that it is 
new. The grease on the hands will sometimes 
cause failure in a connection of this kind, 
especially if the wire has been handled a lot. 
A light scraping with a knife is sufficient to 
clean the bus bar. 

The wire is now bent into place so that it 
touches the soldering lug on the condenser. 



If possible, arrange this in such a way that the 
wire rests in place by itself. This makes mat- 
ters easier and takes the strain from the con- 
nection. Since solder, like water will not run 
up hill, it will be far easier to make this con- 
nection if we tilt the whole set forward so that 
the lug on the condenser is on top. 

When the soldering iron is sufficiently hot, 
it is dipped for an instant in the paste. A 
bit of this paste is applied with the match to 
the bus bar and the lug. Next take the solder 
and hold it so that a small drop adheres to 
the surface of the iron. Apply the iron to the 
joint then and allow the solder to flow in 
smoothly around the wire and the lug. It is 
not necessary to cover the wire entirely as long 
as it is held securely. Put the iron back to 
heat, and by this time the joint should be 
hardened sufficiently to hold. The next step 
is to wipe it off with the rag. An excellent 
joint results. 

GENERAL ADVICE TO THE SOLDERER 

D EMEMBER that the solder is in a liquid 
1^- form and if you handle the iron too 
quickly it will drop off and possibly burn you 
or your clothing. Remember also that copper 
and brass are good conductors of heat and if 
you handle the parts just soldered too soon, 
you may get a bad burn. Brass binding posts 
particularly, have a way of staying hot for a 
long time and some of the fixed condensers are 
veritable furnaces for holding the heat. In 
fact due to this alone, it is far better to make a 
connection through a fixed condenser with a 
small machine screw rather than soldering the 




RADIO BROADCAST Photograph 
FIG. 6 

Re-tinning the iron. A small can cover containing 
a portion of melted solder and paste flux may be 
employed for periodically re-tinning the iron. The 
flux cleans the soldering iron surface so that the 
solder in the can cover will adhere to it 




RADIO BROADCAST Photograph 
FIG. 7 

How to prepare a joint for soldering. A bit of flux 
is applied, with the aid of a stick or scrap piece of bus 
bar, to the joint to be soldered. This flux cleanses 
both wires so that the solder will stick to them 



wire to it. Many fixed condensers have actu- 
ally been short circuited by the soldering pro- 
cess. 

Do not think that because every joint is 
soldered, the set cannot have a loose connec- 
tion, because this happens far too often. 
Sometimes too much paste applied to a joint 
will cause a layer of this material to harden 
in between the two surfaces. Naturally such 
a condition will make the set very noisy. In 
another case the writer found a set in which a 
soldered connection had completely parted due 



to the fact that the wires had been under too 
much tension when soldered. This joint had 
pulled apart during the set owner's absence, 
and it was only after several evenings of frantic 
effort that the trouble was finally located in 
one of the most inaccessible parts of the set. 

To sum up the whole art of soldering, the 
"artist" must remember just two things. 
Keep the soldering iron clean and the surfaces 
clean. This is the whole secret of the thing. 




RADIO BROADCAST Photograph 
FIG. 8 

The iron should be held firmly on the joint to be 
soldered, touching both pieces so that when they 
become heated, the solder on the tip of the iron will 
flow evenly over the point. Additional solder may 
be fed from the strip solder wire or it may be " picked 
up" from the can cover 



Latest Alterations in Broadcasting Wavelengths 



/COMPLETING the list of Class B broad- 
\**_ casting stations whose wavelengths 
have been realloted by the Radio Service, 
Department of Commerce, the following 
Pacific Coast stations received new wave- 
length assignments: 

KNX " Los Angeles, Calif. 336.9 meters 

KFAE Pullman, Wash. 348.6 

KGO Oakland, Calif. 361.2 

KFOA Seattle, Wash. 384.4 

KHJ Los Angeles, Calif. 405.2 

KPO San Francisco, Calif. 420.3 

KFI Los Angeles, Calif. 468.5 

KGW Portland, Ore. 491.5 

KIX Oakland, Calif. 508.2 



Wavelengths assigned to points where 
broadcasting stations are to be erected were: 

Corvallis, Ore., 280.2 meters, Los Angeles, 293.9, 
Phoenix, Ariz., 299.8, Seattle, Wash., 305.9, Pasa- 
dena, Cal., 315.6; Salt Lake City, 333.1; Missoula, 
Mont., 394.5, and Seattle, 454.3. 

It was recently announced in a news dis- 
patch from Washington that the Radio Ser- 
vice was considering readjusting the entire 
wavelength assignments now in force with 
Class B stations. This would be done in order 
to give each station a separation of fifteen 
kilocycles instead of ten, as is now the case. 
It is not now known when that reassignment 
will take place. 



The Revelations of Enoch 

The Short- Wave Doodlebug Pocket Humor and Radio 
Philosophy Uttered by a New Electro-Optical Discovery 

BY W. R. BRADFORD 



IN THE baseboard that runs around the 
floor of my studio, and radio lab. is a 
hole made by a mouse at some earlier 
time. The hole at present is occupied by 
a Doodlebug, who holds forth there, in bache- 
lor quarters. I had gone to quite some pains 
in making friends with this little fellow, and at 
last succeeded to the point where he would 
poke his head from the hole and look me over 
carefully with his beady, black little eyes. 

As we became better acquainted, I began 
to take liberties. One day I held forth a 
finger for his inspection, and the little cuss 
mounted my finger, whereupon, I lifted him 
to my desk, where reposed a Knockout 
Roberts set. The Doodlebug gazed at the 
set and began to show interest. 

1 made a little ladder and placed it against 
the panel. The Doodlebug climbed the 
ladder! After a careful inspection of the 
set, he turned and waved his antenna in a 
peculiar, jerky manner. Getting no response, 
he repeated this several times. Suddenly I 
discovered he was wigwagging me, in the In- 
ternational code! 

"Make a short wave set," said the Doodle- 
bug: " I want to talk to you!" 

"What wavelength shall 1 make it?" I wig- 
wagged back. 

" Make it one half of one per cent." said the 
Doodlebug. 




Alas! My lab contained no equipment to 
comply with this Volsteadian requirement: 
"Talk with me in wigwag," I signalled: 
"Later on I shall make a set." 

The Doodlebug pulled down his vest, meta- 
phorically speaking, and wigwagged the follow- 
ing: 

NEW RADIO PHILOSOPHY 

RADIO is nothing new to me. I was born 
with it, as all of the insect family are. 
Few of the insects have vocal cords, so we de- 




"THE LITTLE CUSS MOUNTED MY 
FINGER 



ENOCH TESTING A GRID CONDENSER 

And putting the hall mark of approval on it 

pend on radio for our communication. No, 
we have no understanding of the sign language, 
such as your mutes use, though our different 
postures and actions indicate our feelings and 
desires, in a more or less crude manner. But 
our main means of communication is by radio. 
Our waves are similar to those you use, but 
very much shorter. Man may some day be 
able to communicate with us when he under- 
stands our units of measurement, which are 
minute, compared to your methods. 

"We do not receive and send by your 
methods. What you would call nerves, are 
all arranged for, in our antenna, our segmented 
organs of sensation. You depend on sound. 
We feel vibrations. Though these vibrations 
are minute, we can receive and send them a 
considerable distance as much as two hun- 
dred feet. No, we are not bothered with 



The Revelations of Enoch 



101 




IT S A WISE BUG 

That knows its own receiver. Enoch, the confiden- 
tial radio bug, is photographed in a moment of his 
marked preference for the Roberts Knockout set 



static, or extraneous interference. We have no 
'squeal hounds' to make our radio a thing 
to swear at. There is no 'best circuit' with 
us. Each one of us is his own super-hetero- 
dyne, so to speak. Thus, much valuable time 
is saved, which would otherwise be wasted in 
endless wrangling over 'low loss apparatus,' 
and such flubdub!" 

(Did you ever hear the likes of that? The 
very kernel of good, sound radio sense!) 

The Doodlebug continued: "Maybe you 
doubt me? Well, the ignorant ever condem 
that which they do not understand." 

(Get that? That little jasper has read 
Rochefoucauld's Maxims, I betchuh!) 

The Doodlebug waved on: "An ant finds 
an open sugar bowl. He is not like a human 
greedy, and wanting all for himself. No. 
He is one of God's creatures who share with 
others at least, with their own kind. Does he 
waste valuable time running wildly around, 
shouting: 'Oi, yoi, yoi! Come and get a 
mouthful of sugar'? No. He broadcasts the 
news with his own little station his nerves, 
and his antenna. Each ant's sensory appara- 
tus, his antenna, is tuned to the same wave- 
length, which never varies. All the ants 



within range of his broadcast come and tune 
into the feast until one of you humans turn 
loose with a howitzer loaded with insect 
powder." 

(So that was the way ants learned of sugar 
banquets! Come to think of it, it must be so. 
One time an ant crawled down my back and 
took his broadcasting station with him. In- 
side of two minutes, a string of ants had begun 
to crawl up my trouser leg! I'll wager the 
explorer ant got lonesome, and broadcast for 
company !) 

Just then Mrs. Betterhalf called: "The fur- 
nace needs attention!" Quick as a flash the 
Doodlebug ran down the ladder and made for 
his hole in the baseboard. 

Bachelor Doodlebug? Such actions denote 
fear of the feminine, and indicate that this lit- 
tle rascal at some time had some unpleasant 
matrimonial melange. (I fear the plot is 
going to thicken somewhere.) 

His actions brought to mind those of a comic 
character of mine, so I named him Enoch. 
Enoch, you remember was afraid of his wife. 

I shall make a short-wave set. The shorter 
the better, evidently. Then in our next inter- 
view we may learn more about short-wave 
radio and other things. We shall see. 

(As Enoch hurried to his hole, I pot-shotted 
him with my faithful camera. Doesn't it 
make a nice little tail piece, for a story finish? 
Thanks. I thought you'd like it.) 




2iiiiiiimiiiiiiiiiimiiiiiiiimiimiiiiiiiiiiiiiimiimiiiiiiiimiiiiiiiiiiiiimiiiii iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiMiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiniitiiiiiiiiiiiiiiiiMiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiu 

["NO\X/ I HAVE FOUND. ... . " 

A Department Where Readers Can Exchange Ideas 
and Suqaestions of Value to the Radio Constructor andOperator I 

3 r 



ALTERNATING CURRENT AS A 
SOURCE OF FILAMENT SUPPLY 

RECENTLY I have been experimenting 
with alternating current as a means 
of heating the filaments of vacuum 
tubes. The idea is, of course, an old one, 
but for some reason has never been put into 
practice to any great extent. Alternating 
current cannot be used satisfactorily to heat a 
detector tube filament. This article will be 
confined to a discussion of the use of alternating 
current in amplifiers. 

With the advent of the dry cell tube our 
troubles concerning filament supply would 
seem to be ended. However, these small 
tubes are so designed that they are unable to 
handle much power and hence are not very 
satisfactory as audio-frequency amplifiers, es- 
pecially in the second stage. For tubes re- 
quiring more than .25 ampere filament cur- 
rent, dry cells are uneconomical. 

The difficulty to be overcome when alter- 
nating current is used, is the hum which is 
produced in two ways: 

1. If the grid return be connected to either end 
of the filament, then the grid potential becomes al- 
ternately positive and negative with respect to the 
midpoint of the filament. If it were possible to 
connect the grid return to the midpoint of the fila- 
ment, then, of course, its potential would not change. 
This cannot be done but a trick may be employed 
which by means of a potentiometer, as shown in Fig. 
i, the same results may be produced. Here we see 
that the midpoint of the potentiometer remains at 
constant potential, namely, the same potential as 
the filament midpoint. Hence, by adjusting the 
potentiometer we can make the grid return remain 
at this same potential. This simple adjustment is 
easily made and the hum reduced to a very small 
quantity. 

2. The temperature of the filaments does not re- 
main constant, but changes continually from a max- 
imum value to a minimum value as the current 
through the filament passes through its cycle. zero, 
positive maximum, zero, negative maximum, zero. 
See Fig. 2. 

For the usual house lighting supply, the 
frequency is 60 cycles per second. The fila- 
ment temperature, therefore, reaches its max- 



imum and minimum temperatures 120 times 
per second. This produces an audible hum 
in the phones at a frequency of 120 vibrations 
per second. It is interesting to check this 
value against the tone of B below middle on a 
properly tuned piano. If middle C is 256 
vibrations per second, then B, an octave below, 
is about 123 vibrations per second. By listen- 
ing to the hum produced in the phones when 
the potentiometer arm is properly adjusted 
for constant grid potential, and comparing this 
hum to B below middle C, we cannot detect 
the three cycles difference. 

If the potentiofneter arm be moved so that 
the grid return is connected to one end of the 
filament, instead of midway between its two 
ends, then the grid potential varies with re- 
spect to the filament at the rate of 60 cycles 
per second. This, of course, causes a 60 cycle 
hum in the phones in the plate circuit. If we 
actually move the potentiometer arm away 
from its mid position and at the same time 
listen in the phones, we hear the 120 cycle 
hum gradually become lost in the 60 cycle 
hum, as the latter increases in amplitude the 
further we move the potentiometer arm from 
its midpoint. 

Well, all this theory sounds very fine, but 
what good is it? In answer to this I shall 
describe briefly a single-stage audio-frequency 
amplifier which I have constructed employing 
the potentiometer feature as outlined, and find 
entirely satisfactory from every standpoint. 
The quality of reproduction is good, the vol- 
ume is ample, and there is no noticeable a. c. 
hum. The loud speaker which I am using is 
merely a fibre megaphone about 2 feet long 
with a wye victrola headset connector soldered 
to it, and a pair of Western Electric phones. 
The quality of reproduction is better than 
many loud speakers now on the market. 

Now for the amplifier itself. The apparatus 
required: 

An audio-frequency amplifying transformer. 
Rheostat, tubes, socket. 
Potentiometer (200 ohms or more). 

The apparatus is assembled in a manner 
similar to the usual audio-frequency amplifier. 
The rheostat must be placed between the 



"Now, I Have Found 



103 



potentiometer and the a. c. supply as shown. 
See Fig. 3. 

I am using this amplifier in conjunction with 
a one-tube reflex set. This tube is a uv-igg, 
and its filament supply consists of three dry 
cells in series. The proper negative grid bias 
for the audio amplifier tube may be obtained 
either from a separate C battery, or, by con- 
necting the A battery of the first tube so that 
it acts as C battery for the second. This is 
shown in Fig. 3. 

The value of C battery which will give un- 
distorted amplification depends upon the type 
of tube used and also upon the plate voltage. 
For 200 and 300 tubes, use about 1.5 volts. 
For 20 1 -A and 301 -A tubes use 1.5 volts for a 
plate voltage of 40 volts, and 4.5 volts for a 
plate voltage of 90 volts. 

The a. c. supply for filament must of course 
be transformed from 1 10 volts to a lower value. 
This is most economically done by means of a 
toy transformer which can be purchased for 
a couple of dollars. The secondary voltage 
may be from 5 to 10 volts. Most storage 
battery tubes are designed to operate at a 
filament voltage of 5 volts. I am using a 
uv-200 tube, consuming a filament current 
of i ampere. The secondary of my trans- 
former gives me 5 volts. The type of rheo- 
stat used depends upon the tube. In this 
circuit, a 6 ohm rheostat is used. 

In order to find out the resistance of the 
rheostat necessary, first determine the normal 
filament voltage and current of your tube and 
the secondary voltage of your transformer. 
Subtract the filament voltage from the trans- 
former voltage and divide by the current. 
This gives the value of normal resistance in 
series with filament. The rheostat should, 
to allow for discrepancies, have a somewhat 
higher resistance than this computed value, 
say 25 per cent. For example: 

Given 

Filament voltage 5 volts. 
Filament current j ampere. 





Transformer secondary voltage 8 volts. 
8 5 volts = 3 volts. 
3 -i- j = 12 ohms. 

Adding 25 per cent, we get 15 ohms as the 
resistance of the rheostat. It can be seen 
from the above that any value of transformer 
voltage may be used provided the rheostat 
resistance is properly computed. 

I use only one stage of amplification on my 
set because the resulting volume of signal is 
quite sufficient. However, there is no reason 
why two stages cannot be used, employing a 
common potentiometer and filament rheostat. 
The rheostat as determined for one stage may 
also be used for two stages. 

Of course, the filament transformer may be 
constructed without much trouble, but its 
specifications will not be given here. 

The audio amplifier using a storage battery 
may readily be converted to use a. c. merely 
by the addition of the potentiometer. The 
total initial cost of the a. c. amplifier is less 
than the usual method and its upkeep is less. 
Another point of some importance is the fact 
that tube filaments have a longer life when 
heated with a. c. than when d. c. is used. -J. 
B. CLOTHIER, JR., Lansdowne, Pennsylvania. 

A SCREW STARTER 

WHEN constructing radio sets it is often 
difficult to hold the screws so that 
they may be put in some nearly in- 
accessible place. An efficient device may be 
made by slotting a piece of quarter-inch brass 
rod about six inches long, with a hack saw, for 
about a half inch. In this slot two phosphor 
bronze strips about an inch and a quarter long 
are inserted and soldered in. The tips are then 
filed so that they will be thin enough to insert 
in the slots of small screws. They are then 
sprung so that their natural position is with 
the ends about an eighth of an inch apart. 
When these tips are pressed together and 
placed in the slot in the screw, and then re- 



A.F.T. 



To phones or 
2nd amplifier 



Rheostat 

A A.C. 6 



One complete cycle 
for 60 cycle current 



FIGS. I, 2, AND 3 




To 

stepped-down 
A.C. supply 



104 



Radio Broadcast 



-Shape as desired 



Phosphor Bronze Spring 
/ strips soldered in 
/ saw slot 



I /A Brass rod 
/ 6" long 



FIG. 4 

leased, they will hold the screw securely until 
it has been started, and then it can be released 
by simply pulling. The sketch, Fig. 4, shows 
the details. 

A CONVENIENT MOUNTING STRIP 

A VERY practical method of installing 
a receiver is to bring all battery 
leads up through the top of the op- 
erating table, to binding posts mounted on a 
strip of bakelite which is fastened to the table 
top. Fig. 5 shows the details. This not only 
provides an exceptionally neat installation 
by keeping all wires and batteries out of the 
way, but will be found very advantageous 
whenever it is necessary to change from one 
receiver to another, or to test out any receiving 
set. The A battery and B battery posts are 
not connected in any way, due to the indi- 
vidual requirements of the various circuits, 
but these connections can be bridged across 
from one post to another, if such connections 
are not taken care of in the wiring of the re- 
ceiver itself. 

Short pieces of wire are run from the posts 
on the mounting strip, to the posts at the rear 
of the receiver, and when taking off one receiv- 
ing set to try another, it is merely necessary to 
loosen the binding posts on the table, allowing 
the connecting wires to remain attached to the 
receiving set, and they will then be in proper 
position for re-connecting. 

This method of bringing antenna, ground, 
and battery leads to a receiving set will im- 
mediately find favor v/ith all experimenters 
who ever have occasion to disconnect one 
receiver to test out another circuit. HARRY 
W. GILLIAM, Big Stone Gap, Virginia. 

(Bakelite strip 14 V 1 1 / 2 ' 3 /is 



Mounting' 
Screw 



'Binding Posts . 



Bakelite 
binding post 
TV strip 






Hole through s 
Table Tc?. 




Table Top 



A GOOD FILTER CONDENSER 

NO DOUBT many readers were very 
much interested in the B battery from 
the lamp socket, as described by Mr. 
Le Bel in the September, 1924, RADIO BROAD- 
CAST. Perhaps they may also be interested in 
the following description of an electrolytic 
condenser for use in such an outfit. 

The condensers built by the writer and 
used in this outfit were made as described be- 
low and as illustrated by the sketch, Fig. 6. 
Each condenser required one large mouthed 
glass jar, a hard rubber or wooden top, an 
aluminum sheet, a quarter inch diameter 
steel rod and an electrolyte of ammonium 
phosphate in pure water. The aluminum 
sheets used were four inches wide by five feet 
long and one sixty-fourth inch thick. A 
small tab or ear was left on each for making a 
connection. The sheets were rolled into a 
spiral as shown. The steel rod is for making 
contact with the solution. 
- After the parts are assembled and the so- 
lution poured into the glass jars, the plates 
must be formed by passing a current through 
the condensers. This may be done by con- 
necting a 100 watt lamp in series with them 
and plugging the circuit into a lamp socket.. 
It takes a long time to form the plates but it 
can be done with a little patience. When the 



Aluminum Sheet 
coiled into Form 




%dia. Steel Rod< N 



Glass Jar- . 



35 


il rT 




Hard Rubber 


HIM. 


i i 1 ll 


mill! 












k Cjl 1 

1 

1- 


-J ^vl 


ij 




' 
1 




'I, 




II. 1 


' 






H 




ji 


, -Aluminum 
Sheet 


" ! 

1 ' 

|| L.J 

ll 
Jl 









FIG. 5 



FIG. 6 



"Now, I Have Found 



IQ5 



forming is advanced far enough a good spark 
should occur when the condenser is short 
circuited after a charge. 

A pair of these is now working very well in a 
lamp socket B battery outfit. The residual 
hum is small enough to be negligible and it 
seems to become less with use. This outfit 
is supplying the plate potential for a Roberts 
Knockout circuit in very satisfactory fashion. 
C. E. SEIFERT, Cincinnati, Ohio. 

MAKING YOUR OWN CABINET 

THE average amateur makes a very poor 
job of his cabinet, which spoils the ap- 
pearance of an otherwise good receiver. 
The following is a description of how to make 
it look like a factory job with a piano finish, 
without the use of a lot of clamps. 

It is possible even to use an old walnut sew- 
ing machine top for the wood. The general 
specifications are outlined in Fig. 7. 

The joint at "a" is glued, but clamps are not 
required- to- hold it.- It is sawed .as in "b." 
First use a marking gauge, place a back on the 
line to keep the saw straight, or use a mitre 



box if one is available. Next use a chisel on 
the end to cut it out. 

Then bore three holes in each side piece for 
round headed brass screws as at "a," place the 
back of the case in a check and mark the holes 
through; but when drilling allow a little 
draught to draw pieces up tight, as in C. 

This will bring the pieces up tight when 
glue and screws are applied so that the joint 
will not show. The bottom moulding is in 
two pieces. The top bead is a strip \ x ij 
inches with outside edge rounded and corner 
mitred' shown at "b." 

The base "c" is moulded with two chisels: 
one is a core box gouge, and the other a plain 
flat chisel. This is quite easy to do. When 
finished, scrape and sandpaper. The top 
bead "b" is then glued to the base "c." 

After the case is together, get a bottle of 
white shellac and a small sponge. Apply three 
coats with the sponge, one right after the other 
as soon as dry. Allow about twenty minutes 
between coats. Then have a small piece of 
cotton batting tied up in a piece of woolen rag, 
wet this in alcohol and rub all over the case 
well. Now go all over the case with a piece 



Saw, 



..Block to 
' guide saw 



-E 




e 



b 

strip 



1 



O) 



S \y* 



-JlftV- 



nc. 7 



io6 



Radio Broadcast 



of tallow, then dust on rotten stone from a 
woolen bag and rub well with the heel of the 
hand and a clean rag. The more you rub 
the better the finish. Try it and see; the fin- 
ish will look like a piano, provided the wood 
is smooth when you start. WELSFORD A. 
WEST, Hopewell, Nova Scotia. 

A TICKLER KINK FOR THE ROBERTS 

AFTER trying every conceivable way of 
working the tickler for my Roberts 
set, I have devised the scheme shown 
in Fig. 8. I have found it more satisfactory 
mechanically and electrically than the factory- 
made apparatus. 

This arrangement cost me thirty cents (not 
including coils). It is made from the hard- 
ware of a 1 80 coupler bought at a five and ten 
cent store. 

As will be seen, the tickler coil is brought 




P&N 



*2 



P&N-x 



i 1 iii i'3fa Minimi 
IjU, / Coupli 



T 

Minimum 
Coupling 



^////^/////////////////W 



Panel' 



FIG. 8 



into the field of the S 3 coil very gradually by 
turning the dial. 

Another feature is the small amount of 
space required behind the panel; it is about 
25 inches. 

The coils are wound on standard forms, the 
T coil being cut smaller than the others. 
J. BELL, Ottawa, Canada. 

WHEN WORKING BAKELITE 

TO SQUARE up the edges of bakelite, a 
common wood plane may be used if it 
is set rather finely. 

An excellent and rather Unusual finish may 
be given bakelite by inserting in the chuck of 
a drill press, a piece of wood about f inch in 
diameter, and bringing this down on the sur- 
face of the bakelite so that the circles produced 
will overlap slightly. The finish is similar to 
that given the armor plate of safes, and when 
done evenly, gives a very pretty effect. It 
is best to practice on the wrong side of the 
piece or on a scrap piece until the knack is 
acquired. CARL PENTHER, Oakland, Cali- 
fornia. 

DULL FINISH FOR PANELS 

THE instructions usually given for remov- 
ing the gloss finish from bakelite, formica, 
or condensite panels, are to rub them 
down with No. o sandpaper and oil. How- 
ever, in practice I have found that a very 
smooth yet dull finish, with no scratches, is 
more easily obtained by rubbing the panel 
down with No. oo steel wool, dry. Oil may 
be used with the steel wool, or applied after- 
ward, but is not at all necessary. The di- 
rection of rubbing should be back and forth, 
lengthwise with the panel. After the panel is 
rubbed down in this way, it is very easy to 
mark locations on it with a sharp lead pencil, 
when laying it off preparatory to drilling. 
HARRY W. GILLIAM, Big Stone Gap, Vir- 
ginia. 



FOR a long time, RADIO BROADCAST has felt the need of an outlet for the many excellent ideas dealing 
with various features of radio construction which reach our office. If you have an idea about a valuable 
and useful new circuit, some new device, a construction or operating suggestion, we should like to have it. 
Payment of from two to ten dollars will be made for every idea accepted. The description should be 
limited to three hundred words and typewritten. Accompanying sketches, drawings, and circuit diagrams 
should be as plain as possible. We do not want simple, obvious suggestions. Material to be acceptable 
for this department must offer something of definite value to the constructor. Mere novelty is not 
desired. Address your manuscripts to this department. RADIO BROADCAST. Garden City, New York. 




QUESTIONS AND AN$WRc/ 

\J3 



See Important Special Announcement on Page 112 

QUERIES ANSWERED 



HOW MAY I USE A VOLTMETER AND MILLIAMMETER 
IN A RADIOLA SUPER-HETERODYNE CIRCUIT? 

C. J. M. Pittsburgh, Pennsylvania. 

I WISH TO ADD A STAGE OF R. F. AMPLIFICATION TO 
MY REGENERATIVE RECEIVER. HOW SHALL I DO IT? 

W. D. M. Worcester, Massachusetts. 

WHERE MAY i OBTAIN A COLLEGE CORRESPON- 
DENCE COURSE IN RADIO? 

L. G. B. Wilkes-Barre, Pennsylvania. 

WlLL YOU PUBLISH A CIRCUIT DIAGRAM SHOWING 



HOW TO USE STRAIGHT AUDIO, PUSH-PULL, OR RE- 
SISTANCE-COUPLED AMPLIFICATION WITH THE TWO- 
TUBE ROBERTS CIRCUIT? 

K. H. Burlington, Vermont. 

I HAVE BECOME CONFUSED WITH THE MARKINGS 
ON AUDIO-FREQUENCY TRANSFORMERS. WILL YOU 
EXPLAIN THE PROPER MARKINGS AND CONNECTIONS? 

. - B. W. E. Roanoke, Virginia. 

HAVE YOU ANY OTHER ADDITIONAL NOTES ON THE 
ROBERTS CIRCUIT? 

C. T. S. El Paso, Texas. 



METERS AND B BATTERIES 

HERE again we discuss the specific problem of 
the use and aid of meters in the B battery 
circuit of a Radiola super-heterodyne to 
determine the state of life of these batteries. 

A milliammeter (o 100 milliampere scale) when 
placed in the circuits as shown in Fig. i, A-B-C and 
D registers the drain upon the B batteries in milli- 
amperes. This meter itself does not consume any 
of the energy as it is of low resistance. It may be 
permanently included in the circuit. 

The full B battery drain will be indicated when 
the meter is connected in the terminal as in D, be- 
cause this is the common return lead of the battery 
for both 45 and 90 volt terminals. In C only the 
45 volt drain would be indicated, and in B only the 
amplifier drain would be manifest. 

The voltmeter (with a scale reading from o to i 50 
volts) is used to indicate the state of voltage of the 
B battery. When voltage tests are made, the 
terminal leads of the meter should only be momen- 
tarily touched to the B battery. 

The resistance of a voltmeter is such that a leak- 
age path would be provided for the B battery cur- 
rent, and would soon discharge the battery, making 
it inoperative. Therefore it is not well to connect 
the voltmeter permanently across the B battery 
terminals. A switch may be provided which will 
connect it in the circuit for momentary readings. 

The milliammeter and voltmeter afford all definite 
check on the life and condition of the B batteries 
and should be included in all installations, especially 
where many tubes are employed. 



ADDING R. F. AMPLIFICATION TO REGENERATIVE 
RECEIVERS 

A METHOD for adding radio frequency ampli- 
fication to a regenerative receiver was dis- 
cussed in the March, and May, 1924, RADIO 
BROADCAST, but as these issues are out of stock at 
Doubleday, Page & Co., the subject will be briefly 
treated here. 

The problem to be considered in an addition of 
this kind is to construct an amplifier which will not 
radiate of itself into the antenna or pass along the 
oscillations of the regenerating detector. 

The coupler T-i , in Fig. 2, is of the standard type, 
a primary with a secondary of about 50 turns 
shunted by a .0005 mfd. variable condenser. The 
primary may be variably coupled to the secondary. 
A tube socket, rheostat, .002 mfd. fixed condenser and 
200 ohm resistance is all that is otherwise necessary. 

The primary of the regenerative receiver serves 
as the plate coil of the amplifier. Radiation is 
prevented by the use of the 200 ohm resistance, 
which may be termed a losser, in series with the high 
voltage lead of the B battery supply. 

Fig. 3 shows the Roberts form of amplifier which 
is highly recommended. Here, the plate coil of 
the amplifier must be specially wound with a pair of 
wires. The inside lead of one coil connects to the 
grid of the tube through a neutralizing condenser, 
and the outside lead of the other coil connects to the 
plate. The remaining two leads are connected to- 
gether and thence connected to the high voltage B 
battery lead. The antenna coupler is of the stand- 
ard type. 



io8 Radio Broadcast 

To Interior of Receiver 



\- To -8 Battery 
Terminal 



Position of Meter 

when used in 

this circuit 



-B- 




/To Interior of Receiver 



B- 



mi i nun 




8- 



-A- 



t ---- To Interior 
of Receiver 



-C- 




B- 



WILUAMPERE READING 
FOR45V."B"TAP 




90 VOLT 8 AMPLIFIER DRAIN 



To Interior of Receiver, _ 



B + 45 



11,11 

FULL DRAIN READING 



B + 90 



COLLEGE RADIO CORRESPONDENCE COURSES 

INTENDING in no way to discriminate, this 
department can advise that for those wishing to 
further their radio studies the course as outlined 
by the prospectus of the Department of Engineering 
of the Pennsylvania State College, State College, 
Pennsylvania, is especially interesting. 

Two courses are provided, one, elementary, cover- 
ing the principles of radio electricity how tele- 
phone, crystal, and vacuum tube sets work 
amplification, etc. working drawings for eight 
typical receivers discussions on topics such as 
static, directional effects, radio-photography, test 
methods, etc. This course is of ten assignments 
and costs f 10.00. 

The advanced course is also in ten assignments 
and the price is $i 5.00. It applies to technical men 
and amateurs, desiring the mathematical treatment 
of the subject, together with the electrical theory 
involved. It covers elementary electricity, radio 
circuits, electromagnetic waves, damped wave 
transmission, the electron tube, apparatus for recep- 
tion, the tube as a generator, radio telephony, etc. 



, REGENERATIVE DETECTOR 



AUDIO AMPLIFIER 



CIRCUITS FOR 
RECEIVER 



THE ROBERTS 




IT IS to be' remembered that the original two- 
tube Roberts circuit already contains one stage 
of audio-frequency amplification in the reflexed 
first tube. Now, in the addition of amplifiers the 
following has been determined: 

i. The standard straight stage of audio usually 



REGENERATIVE DETECTOR 




A - - B5 



FIG. 2 



FIG. 3 

overloads and causes distortion unless the trans- 
former secondary is shunted by a variable resistance 
of a value of 10,000 to 100,000 ohms. The full 
amplification factor of the stage is not realized be- 
cause of the inclusion of this "losser" . 

2. The push-pull amplifier is admirably suited 
for controlling the output of the two-tube receiver 
and will furnish plenty of volume. However, as is 
the case with all audio-frequency transformers, the 
quality of reproduction is slightly affected because 
the amplification characteristic of the transformer 
favors some band of frequencies over others. 

3. The resistance-coupled amplifier will not pro- 



RADIO BROADCAST ADVERTISER 



109 



V ^fZ* ^f mm 

BCIS ! not Fancier 




Do you. hnow 

Where Condenser losses 

Come -from? 

RESISTANCE LOSSES are 

, the losses which most serious- 
ly affect the efficiency of aconden- 
ser when at working radio fre- 
quencies. They arise from poor 
contacts between plates and from 
poor bearing contacts. Soldered 
plates and positive contact spring 
bearings reduce these losses to a 
minimum, 

Eddy current losses occur in 
metal end plates and the conden- 
ser plates themselves. While not 
so serious as resistance losses, 
they increase with the frequency, 
and therefore should be kept as 
low as possible. 

Dielectric losses are due to ab- 
sorption of energy by the insulat- 
ing material. Inasmuch as they 
vary inversely as the frequency, 
they have less effect upon the 
efficiency of a condenser at radio 
frequencies than any other set of 
losses. The use of metal end 
plates in short-wave reception to 
eliminate dielectric losses is never 
justified, because they introduce 
greater losses than well-designed 
end plates of good dielectric. 



The design of General Radio Condensers 
is based on scientific facts and principles, 
not on style and fancies. 

Specially shaped plates always in perfect 
alignment give the uniform wave-length 
variation which, permits extremely sharp 
tuning. 

Rotor plates are counterbalanced to make 
possible accurate dial settings. 

In 1915 the General Radio Company in- 
troduced to this country the first Low Loss 
Condenser, and ever since has been the 
leader in condenser design. 

Lower Losses and Lower Prices make 
General Radio Condensers the outstanding 
values of condenser design. 

Licensed for multiple tuning under Hogan 
Patent No. 1,014,002 



$CJOO 



Type 247-H, with geared Vernier 
Capacity, 500 MMF. Price 

Type ;247*F, without Vernier 
Capacity, 500 MMF. Price 



GENERAL RADIO CO. 

CAMBRIDGE, MASS. 




Quality Parts 



Tested and approved by RADIO BROADCAST 



no 



Radio Broadcast 



duce as much volume as the push-pull amplifier hut 
will be faultless in quality when properly adjusted. 
In all three types of amplifiers, the input connects 
to the two central blades of the double circuit jack. 
The diagram, Fig. 4, is self-explanatory. 

AUDIO TRANSFORMER MARKINGS 

THE designations of binding post markings on 
audio-frequency transformers have become 
standardized to a great extent, but there are 
still some that do not follow general practice. 

In Fig. 5, the binding post marks coincide with 

2 TUBE ROBERT5CIRCUIT 



1 STAGE 
STRAIGHT AUDIO AMPLIFICATION 





- A - B- B 

45V 90V 

FIG. 4 

the markings as applied to circuit diagrams. Fig. 
6 shows how the marks appear when the primary 
posts are turned the other way around. The out- 
side lead of the secondary is the point of high po- 
tential in the secondary circuit and usually connects 
to the grid. Standard practice has it that the out- 
side of the primary should then go to the plate. 
However, be sure to have the grid connected to its 
proper post, then if results are not as expected it is 
well to try reversing the leads to the primary of the 
transformer. This is especially important in reflex 
circuits such as the Roberts. 

NOTES ON THE ROBERTS CIRCUIT 

THOSE who used Sickles coils in the Roberts 
circuit may have found that it was not pos- 
sible to tune to the lower wavelengths. This 
is especially true of the first lot of Sickles coils 
manufactured. The condition may be remedied in 
two ways: 

1 . Change the connection of the return side of 
the secondary to the negative side of the A battery 
line instead of the positive, as is commonly shown 
in the circuit diagrams. 

2. Remove five or six turns from the NP and 
tickler coils. 

When removing turns from the tickler coil simply 
unwind them from the outside of the coil. When 
removing turns from the NP coils, unsolder the 
outside ends of both the green and white wires, and 
unwind both of them together until you have taken 




-I- 



-A 



PUSH-PULL 
AUDIO AMPLIFICATION 



I 

rtVi. 

\ 




1 ' 

O 

o 



o 



r 


1 






+ 90-120V 



2 STAGES 

RESISTANCE COUPLED AMPLIFICATION 
i006mfd. i|.006mfd. 




Top view of 

Audio Frequency 

Transformer 

/Secondary, 



FIG. 5 





- Primary" 

Top view of 

Audio Frequency 

Transformer 




FIG. 6 ] 



off six turns, then connect the green and white wire 
exactly as they were connected before. 

This will make your set operate perfectly down to 



I?ADIO BROADCAST ADVERTISER 



111 



Lacault Scores A&ain/ 




'528 

005 m.f.d. Capacity 



i The new Ultra-Lowloss con- 
dfenser is the latest radio improved 
device designed by R. E. Lacault. 
formerly Associate Editor of 
Radio News, the originator of 
Llltradyne Receivers and now Chief 
Engineer of Phenix Radio Corpor- 
ation. 





CONDENSER 




:Simpliflcs radio timing. IVncil- 
record a station on the d'al 
thereafter, simply turn the tlnd-r 
to your pencil mark to get that 
station instantly. Easy quick 
to mount. Eliminates fumblinc, 
guessing. Furnished clockwise or 
anti-clockwise in gold or silver 
finish. Gear ratio 20 to 1 
Silver J2.50 Cold $3.50 



/T IKE every Lacault development, this new Ultra-Lowloss Con- 
J-' denser represents the pinnacle of ultra efficiency overcomes 
losses usually experienced in other condensers. 

Special design and cut of stator plates produces a straight line 
frequency curve, separates the stations of various wave lengths evenly 
over the dial range, making close tuning positive and easy. 

With one station of known frequency located on the dial, other 
stations separated by the same number of kilocycles are the same 
number of degrees apart on the dial. 

In the Lacault Ultra-Lowloss Condenser losses are reduced to a 
minimum by use of only one small strip of insulation, by the small 
amount of high resistance metal in the field and frame, and by a 
special monoblock mounting of fixed and movable plates. 

At your dealer's, otherwise send purchase price and you will be 
supplied postpaid. 




Design of lowloss coils furnished free with each condenser for amateur and 
broadcast frequencies showing which will function most efficiently with the 
condenser. 



This seal on a radio product is 
your assurance of satisfaction and 
guarantee of Lacault design. 



To Manufacturers Who Wish to Improve Their Sets 

The Ultra-Lowloss Condenser offers manufacturers the opportunity 
to greatly improve the present operation of their receiving sets. 

Mr. Lacault will gladly consult with any manufacturer regarding 
the application of this condenser to his circuit for obtaining efficiency. 



PHENIX RADIO CORPORATION, 116-C East 25th St., New York 



Tested and approved by RADIO BROADCAST 



I 12 



Radio Broadcast 



one hundred and eighty meters and will not in any 
way weaken the received strength of the long wave- 
length stations. If for any reason you cannot get 
regeneration at five hundred and fifty meters in- 
crease the detector plate voltage. 

When mounting the Sickles coils in the four-tube 
Roberts layout, the planes of the coils are practically 
opposite to that arrangement employing the Nazeley 
spiderwebs. The builder must exercise his own 
ingenuity in the proper placement of his coils so that 
they will not hinder the action of the variable con- 
densers and he must make sure that the action of the 
tickler coil be not restricted. 

The antenna coupler may be mounted directly on 
the panel slightly below the switch blade. This 
brings the tap leads quite close to the switch points. 
It also allows ready adjustment of the coupling 
between the primary and secondary. 



Antenna Coupler Unit 

mounted directly 
behind and below 
switch points 




The arrangement is as shown in Fig. 7 and permits 
of short leads to both switch points and variable 
condenser. A binding post strip may be mounted 
directly behind the tickler coil to accommodate the 
flexible leads from the tickler and the bus bar 
connections to it. 



PHOUSANDS of you are writing the Grid for technical advice every month. The expense 
JL of framing a complete and exhaustive reply to each letter is very high. The editors have 
decided that the benefit of the questions and answers service will continue to be extended to 
regular subscribers, but that non-subscribers, from April 15 on, will be charged a fee of $1 for 
each letter of inquiry which they send to our technical department. Very frequently, our 
technical information service proves of definite money value to you who write us, for we are 
often able by a sentence or two of explanation, to put you on the right path before you have made 
a perhaps expensive mistake. 

The occasional reader of RADIO BROADCAST will be charged a fee of $1 for complete reply 
to his questions, and the regular subscriber can continue to take advantage of the service as before. 
In that way, the non-subscriber will help share the cost of the technical staff whose service he 
gets. Every letter receives the benefit of the experience of the editor and the technical staff 
and every correspondent may be sure that his questions will receive careful consideration and 
reply. 

When writing to the Grid, please use the blank printed below. 



GRID INQUIRY BLANK 
! Editor, The Grid, 

| RADIO BROADCAST, 

! Garden City, New Yor\. 
\ Dear Sir, 

Attached please find a sheet containing questions upon which kindly give me fullest possible 
! information. I enclose stamped return envelope, 

(ChecJ^ the proper square) 
! [U / am a subscriber to RADIO BROADCAST. Information is to be supplied to me free of 

charge. 
EH / am not a subscriber. I enclose $1 to cover costs of a letter answering my questions. 



I My name is 



I My address is- 



RADIO BROADCAST ADVERTISER 



113 



The two outstanding 

parts in radio! 



Give low losses and amplification 
without distortion to any set 




QUALITY and distance are 
what a radio set must give. 
To insure Quality, amplification 
without distortion is essential. 
And to insure Distance, low losses 
are essential. That is radio in a 
nutshell. 

People in whose sets Acme 
Transformers are used, are sure 
of hearing concerts "loud and 
clear" so a whole roomful of 
people can enjoy them. 

The Acme A-2 Audio Amplify- 
ing Transformer is the part that 
gives quality. It is the result of 
5 years of research and experi- 
menting. It gives amplification 
without distortion to any set. 
Whether you have a neutrodyne, 
super-heterodyne, regenerative 
or reflex, the addition of the Acme 
A-2 will make it better. 



To get the thrill of hearing dis- 
tant stations loud and clear, your 
set must have low losses, for it is 
low losses that give sharp tuning 
to cut through the locals, and it 
is low losses that allow the little 
energy in your antenna to come 
to the amplifier undiminished. 
That's what the Acme condenser 
will do for any set. And it will do it 
for years because the ends can't 
warp, the bearings can't stick and 
the dust can't get in and drive up 
thelosses several hundred per cent. 

The Acme Reflex (trade mark) 
owes its success and its continued 
popularity to these two outstand- 
ing parts in the radio industry, 
for low losses and amplification 
go hand in hand. 

Use these two parts in the set 
you build. Insist on them in the 



set you buy. 
Send 10 cents for 40-page book, 

** Amplification "without Distortion 1 



Acme A-2 Audio Frequency 
Amplifying Transformer 



WE HAVE prepared a 40-page 
book called "Amplification 
without Distortion." It contains 
19 valuable wiring diagrams. In 
clear non-technical language it 
discusses such subjects as, Radio 
Essentials and Set-building. How 
to make a loop; Audio frequency 
amplifying apparatus and cir- 
cuits; Instructions for construct- 
ing and operating Reflex ampli- 



ACME T 




fiers; How to operate Reflex 
receivers; Antenna tuning cir- 
cuits for Reflex sets; "D" Coil 
added to Acme four tube reflex; 
"D" coil tuned R. F. and Reflex 
diagrams; and several more be- 
sides. It will help you build a set 
or make your present set better. 
Send us 10 cents with coupon 
below and we will mail you a 
copy at once. 



ACME APPARATUS COMPANY 

Transformer and Radio Engineers and Manufacturers 
Dept. F4, Cambridge, Mass. 

SEND THIS COUPON 



ACME APPARATUS COMPANY 
Dept. F4, Cambridge, Mass. 
Gentlemen : 

I am enclosing 10 cents (U. S. stamps or coin) 
for a copy of your book "Amplification with- 
out distortion." 

Name 



Street. 



City. State 



amplification 



Tested and approved by RADIO BROADCAST 



New Equipment 




THE ANDREWS 
PADDLEWHEEL COIL 

A well made inductance 
designed to give a higher 
ratio of inductance to re- 
sistance. The several groups 
of spiral windings are space 
insulated from each other 
without the use of any ad- 
hesives or dope. Tuned with 
a .00025 mfd. condenser, this 
R. F. transformer inductance 
has a range from 200 to 600 
meters. Made by Radio 
Units Inc., Maywood, Illi- 
nois. Price $3.00 





TOGGLE BATTERY SWITCH 

A new battery switch designed for 
use in the radio receiver. It is 
neat in appearance with a pol- 
ished nickel finish and has large 
make-and-break contact surfaces. 
The wide spacing of the terminals 
permits ease in making connections. 
It is easily mounted on the panel 
with only one hole required. Made 
by The Cutler-Hammer Mfg. Co., 
Milwaukee, Wisconsin 



KELLOGG CONDENSER 

A low loss variable condenser with a 
heavy brass frame containing a minimum 
amount of metal. Direct three-point 
contact with the rotor assures positive 
connection. A special Kellogg dial in 
conjunction with the vernier attachment 
makes for very fine tuning adjustment. 
Made by the Kellogg Switchboard and 
Supply Co., Adams and Aberdeen Sts., 
Chicago, Illinois 





BALLGRIP SOCKET 

A molded bakelite socket of unusual design. Contact with 
the tube prongs is obtained through a ball socket arrange- 
ment molded into the base of the unit. The construction 
is such as to eliminate the possibility of internal short 
circuiting. Made by Quality Molded Products, Inc., 
1 Exchange Place, Jersey City, New Jersey. Price $1.25 



AMPLION LOUD SPEAKER 

This speaker is designed to give great 
sensitivity and naturalness of tone. The 
Amplion "Floating Diaphragm," kept 
from contact with metal by rubber gas- 
kets, rests on a narrow ledge in the case, 
lightly held there by a spring ring with 
enough pressure to prevent "chatter" 
when extreme volume is desired. Another 
feature of the Amplion is the use of rubber 
insulation between the several sections 
of the horn to eliminate any ring or 
resonance. Made by The Amplion 
Corporation of America, 280 Madison 
Ave., New York City 



RADIO 
BROADCAST 



Vol. 7, No. 2 




June, 1925 



The Story of Broadcasting in 

England 

The Growth of the Radio Giant in Great Britain Compared 
With that in America How John Bull Regulates Broadcast- 
ing The New Radio Import and Licensing Regulations 



By F. J. BROWN 

Late Assistant Secretary of the British Post Office 



BROADCASTING in Great Britain 
began in a very small way by a half- 
hour's transmission of a musical 
program once a week from a station 
belonging to the Marconi Company at Writtle, 
in Essex. This was authorized as a concession 
to the two or three thousand amateurs who at 
that time had received experimental licenses 
from the Post Office, and who wished to test 
the efficiency of their apparatus by picking up 
Writtle's signals. They were mainly gramo- 
phone records, but occasionally more ambi- 
tious programs were introduced. 

This was the limit of development in the 
winter of 1921-2, when I visited Washington 
as Expert Adviser on Communications to the 
British Delegation at the Arms Conference. 
At that time, the broadcasting boom in 
America had just begun. Fortunately, I was 
in a position to receive full information as to 
its progress from my friends General Squier, 
Doctor Austin and Doctor Cohen; and through 
their courtesy I was present at some of the 
meetings of Mr. Hoover's first Radio Confer- 
ence, where I met other world-famous Ameri- 



can radio authorities. An extract from a letter 
which I wrote to one of my colleagues in Lon- 
don on the subject in February, 1922, may be 
of some historical interest : 

The thing which has made the most remarkable 
progress here recently is broadcasting. The num- 
ber of receiving sets which are being used is marvel- 
ous. The Westinghouse people gave it a great 
impetus. They have put up several broadcasting 
stations, and are stated to be selling receiving sets 
(varying in price from $30 to $150) at the rate of 
25,000 a month, and are then quite unable to meet 
the demand. Other people are following suit, and 
it is likely that there are now between 200,000 and 
300,000 receiving sets in use, though the number 
can't be stated exactly, as licenses are not issued for 
reception. The sending stations broadcast on 360 
meters. They probably interfere to some extent 
with ship-and-shore work, and they certainly tend 
to interfere with one another. 1 heard a program 
from one of them last Sunday afternoon at Dr. 
Frank B. Jewett's home, by means of his boy's re- 
ceiving set. Both speech and music were quite 
clear. The opinion is growing here that broadcast- 
ing is the main sphere of wireless in the future. 

On my return to London in March, 1922, I 



Radio Broadcast 



found that applications were being made to 
the Post Office by certain wireless manufactur- 
ing firms for permission to broadcast pro- 
grams of music, etc., for the purpose of 
promoting the sale of their apparatus. 

ENGLAND REFUSED TO GRANT A BROADCASTING 
MONOPOLY 

IT SOON became evident that, within the 
circumscribed area of Great Britain, it 
would be impossible to 
permit the establish- 
ment of broadcasting 
stations with any- 
thing like the freedom 
which was being 
granted in America. 
It was equally con- 
trary to the policy of 
the British Govern- 
ment to grant a mo- 
nopoly of broadcast- 
ing to one, or even to 
two or three, manu- 
facturing firms, as this 
would place them in 
a superior position to 
their competitors for 
pushing the sale of 
their goods. 

In these circum- 
stances, the whole 
question was referred 
to the Imperial Com- 
munications Commit- 
tee. This committee 
is composed of repre- 
sentatives of the 
Army, Navy, Air 
Force, Post Office, 
and other British gov- 
ernment departments 
which are interested in 

wireless. It is presided over by a member of 
the Cabinet, and considers all important 
questions of imperial policy with regard to 
wireless and cables. To this committee I 
explained the position which had arisen in 
America, and the difficulties which were 
presenting themselves in England. 

The Committee recommended that an en- 
deavor should be made to induce the various 
manufacturing firms to cooperate in the 
establishment of a single Broadcasting Com- 
pany, which, it was thought, might be al- 
lowed to establish stations of moderate power 
(say from i| to 3 kilowatts) in eight areas, 
centering on London, Birmingham, Cardiff, 



Facts From Headquarters 

/COMPARISONS, if not exactly odious, 
^ are frequently too easily and carelessly 
made. One hears it said that in England 
the radio people do it this way, or that, 
which is better or worse than our method, 
as the case may be. This story of affairs 
radio in England is authoritative and ex- 
tremely interesting to any one who has 
wondered how England has handled her 
radio problems. Mr. Brown, the author, was, 
until last January, the Assistant Secretary 
of the British Post Office and in administra- 
tive control of broadcasting and other wire- 
less activities for the Government. He tells 
in interesting fashion just what happened 
in England to the licensing system which was 
inaugurated when broadcasting got its real 
start there in November, 1922 exactly one 
year after regular broadcasting service began 
in this country. It was the home construc- 
tor who spoiled the scheme and the revised 
schedule under which receiving licenses are 
now granted takes him into consideration. 
This article by Mr. Brown and "How the 
Government Is Regulating Radio Broadcast- 
ing" by R. S. McBride in RADIO BROADCAST 
for May, are of especial interest because they 
show how the two governments are trying 
to solve their administrative problems. THE 
EDITOR 



Plymouth, Manchester, Newcastle, Edinburgh 
(or Glasgow) and Aberdeen. These stations 
would roughly cover the whole of the country. 
The Committee further recommended that a 
band of wavelengths from 350 to 425 meters 
should be assigned to the stations. They 
considered that the Broadcasting Company 
should not be allowed to broadcast advertis- 
ing matter, or to receive payment for matter 
broadcast. They also considered that, as 
the new organization 
would be placed in a 
privileged position (in 
that no competitor 
would be allowed) it 
was only fair to the 
press and the news 
agencies that its oper- 
ations as a distributor 
of news should be 
rather severely re- 
stricted. They pro- 
posed that its rev- 
enue should be 
provided mainly by 
a share of one-half 
of the license-fee of 
ten shillings (about 
$2.50) collected by 
the Post Office on 
the issue of each re- 
ceiving license. 

In this connection, 
it should be men- 
tioned that, in Great 
Britain (unlike the 
United States), a li- 
cense from a gov- 
ernmental authority 
has always been 
held to be necessary 
for each receiving 
set, as well as for 
transmitting apparatus. 

ENGLISH BROADCASTING BEGAN IN NOVEMBER, 
1922 

MR. KELLAWAY, who was Postmaster 
General at the time (he has since 
become Managing Director of the Marconi 
Company), threw himself into the scheme 
with much avidity; and on May 4th, 1922, he 
announced in the House of Commons that he 
had decided to allow the establishment of a 
limited number of broadcasting stations, and 
was calling a conference of the firms who had 
applied for licenses to open them. This con- 
ference was held a fortnight later and was at- 



The Story of Broadcasting in England 



177 



tended by representatives of twenty-four firms. 
A committee of manufacturers was subse- 
quently appointed by these firms, in conjunc- 
tion with all other firms who were known to be 
engaged in the manufacture of wireless appara- 
tus. Prolonged negotiations took place. 

At one stage, the negotiations almost broke 
down. It seemed to be impossible for the 
manufacturers to agree on the formation of a 
single broadcasting organization: there was a 
marked tendency toward a division into two 
groups, which would have involved the crea- 
tion of two broadcasting companies, each 
representing one of the 
groups. But finally all dif- 
ficulties were surmounted 
and a single broadcasting 
organization was formed 
although it was not until 
January i8th, 1923, that a 
license was actually issued 
to that organization. In 
the meantime (on Novem- 
ber i5th), a daily broad- 
casting service had been 
started at the London sta- 
tion, and later at Birming- 
ham and Manchester. The 
issue of broadcast receiving 
licenses by the Post Office 
began November i, 1922. 

HOW ENGLAND PLANNED 
BROADCASTING 

THE scheme as embod- 
ied in the license to 
the broadcasting organiza- 
tion was recognized from 
the start as being neces- 
sarily of a provisional na- 
ture; and the term of the 
license was accordingly 
limited to two years. The 
principal features of the 
scheme have been officially 
summarized as follows: 

(a) A Company (called the 
British Broadcasting Com- 
pany) to be formed among 
British manufacturers of wire- 
less apparatus. Any such 
manufacturer to be entitled to 
join the Company upon his 
subscribing for one or more 
i shares, and entering into an 
agreement in the form approved 
by the Postmaster General. 

(b The Company to es- 
tablish eight broadcasting 



stations and to provide a regular service to the 
reasonable satisfaction of the Postmaster General. 
The Company to pay a royalty of 50 per annum in 
respect of each station. 

(c) The Post Office to issue broadcast receiving 
licenses at a fee of los. a year, containing a condition 
that the sets used, and certain parts (viz., valves, 
valve amplifiers, head telephones, and loud speakers), 
must bear a standard mark " B. B. C. Type 
approved by Postmaster General." 

(d) The Post Office to pay the Company a sum 
equal to one half of the license fees received in 
respect of broadcast and experimental receiving 
licenses. 




RADIO LISTENERS IN GERMANY 

Broadcasting in the German Republic has not attained as great popular- 
ity as in either England or the United States. England is very com- 
pletely served by a system of master stations and small local relay sta- 
tions. The master stations in the larger centers originate programs of 
their own and relay programs from the London studio of the Broadcasting 
Company. This system, perfectly suited to England, could hardly be 
applied to American conditions. American stations have been "tied" 
together for programs from WEAF, New York, but the "tie-up" has been 
usually with stations only as far west as the Mississippi because of the 
difference in time between New York and the Central and Far West. 
The German enthusiasts here are using a receiver which is incorporated in 
a table lamp. The loop is covered 



1 7 8 



Radio Broadcast 



(e) The sets sold by members of the Company, 
as a condition of bearing the " B. B. C." mark, to 
be British made, to carry a payment to the Company 
in accordance with a tariff approved by the Post- 
master General, and to require the Postmaster 
General's approval of the type of set, such approval 
being confined to securing that the apparatus would 
not be likely to cause radiation from the receiving 
antenna. 

(f) No advertising or paid matter to be broad- 
cast, and only such news as is obtained from news 
agencies approved by the Postmaster General. 

(g) The Company not to pay dividends at a 
higher rate than 75 per cent, per annum. 

(h) An understanding to be given that the re- 
quisite capital would be subscribed, that the service 
would be continued throughout the period of the 
license, and that any deficit should be met. Six 
firms undertook these responsibilities and were 
given the right each to nominate a director, two 
additional directors being nominated by the remain- 
ing firms who might take up shares, and an indepen- 
dent chairman being appointed by the six firms. 

THE RADIO CHILD GROWS 

THE scheme excited much public interest 
and was, on the whole, well received. In 
the winter months following the first issue of 
broadcast receiving licenses by the Post Office 
(on November i, 1922), a considerable number 
of these licenses were sold. By the end of 
March, 1923, the total was about 150,000 and 
the income of the Company from all licenses 
was about 60,000 (about $1,270,000). How- 
ever, at that time difficulties began to be 
encountered. As already explained, the broad- 
cast receiving license was applicable only to 
sets bearing the "B. B. C." mark. But in 
explaining the scheme to the House of Com- 
mons in July, 1922, Mr. Kellaway had given an 
assurance that "provision would be made 
under which amateurs who constructed their 
own receiving sets would be allowed to use 
them." The view then taken by the Post 
Office was that, if a person were sufficiently 
skilled to make his own apparatus, he would 
have sufficient knowledge of the subject to be 
described as an experimenter, and to be en- 
titled to hold the experimental license which 
the Post Office, in its arrangements with the 
Company, had reserved the right to issue in- 
dependently of the broadcast receiving license. 
I will say that the Post Office at that time had 
no adequate conception of the extent to which 
members of the public would make their own 
apparatus. Moreover, on the strength of 
Mr. Kellaway's assurance, firms began to 
place on the market ready-made parts which 
any intelligent person could build up into an 
effective receiving set by the aid of a diagram 



and a screw-driver. Such persons could 
obviously not properly be regarded as "experi- 
menters, and it would not have been fair to 
the Broadcasting Company, and especially to 
the manufacturing firms who constituted that 
Company, to issue experimental licenses to 
such persons, seeing that their apparatus 
carried no royalty payment to the Broadcast- 
ing Company and provided no revenue to the 
manufacturer. 

THEN CAME THE HOME CONSTRUCTOR 

THE Post Office had, indeed, no license to 
fit the case of these persons. The ex- 
perimental license was not applicable, and 
they were not entitled to the broadcast re- 
ceiving license, inasmuch as it covered appara- 
tus bearing the B. B. C. mark only. A dead- 
lock had, in fact, arisen. Many thousands 
of "home constructors" were applying for 
licenses and their demand could not be met. 
What was to be done? Suggestions were 
made from various sources that a new type of 
"constructor's license" should be issued; but, 
although the Broadcasting Company agreed 
in principle to the issue of such a license, 
notwithstanding the fact that they need not 
have done so under the terms of their operat- 
ing license, it proved impossible for the Post 
Office and the Company to arrive at an agree- 
ment as to the precise conditions upon which 
such licenses should be issued. A situation 
intolerable alike to the Post Office, to the 
Company and to the general community hav- 
ing thus arisen, Sir William Joynson-Hicks, 
who was then Postmaster General, referred 
the question to a committee known as the 
Broadcasting Committee. The Committee 
comprised representatives of the Post Office, 
of the Broadcasting Company, of the House 
of Commons, of the radio amateurs and of 
the general public. It held several meetings, 
and gave the most careful attention to the 
whole subject. Finally it recommended sev- 
eral important modifications of the original 
scheme although it recognized that, as the 
original proposal had been embodied in a 
legal agreement between the Post Office and 
the Broadcasting Company, these modifica- 
tions could not be carried out without the 
consent of the Company until that agreement 
had expired at the end of 1924. The sub- 
stance of these modifications was as follows: 

(i) A uniform and simple type of receiving license 
at i os. ($2.50) to be issued and placed on sale at 
Post Offices without any formalities the restric- 
tion against the use of apparatus not bearing the 
"B. B. C." mark being abolished. 



The Story of Broadcasting in England 



179 



(2) The Broadcasting Company to receive a 
maximum of 75.6^. instead of 55. out of the license 
fee, subject to the operation of a sliding scale under 
which the payment per license would decrease as 
the number of licenses increased. 

(3) The method of deriving revenue on royalties on 
the sale of " B. B. C." apparatus to be discontinued. 

(4) Effective measures to be taken to prevent 
evasion of the license, and certain additional statu- 
tory powers to be obtained to strengthen the Post- 
master General's hands. 

(5) The gradual extension of the broadcasting of 
news to be allowed under proper safeguards. 

(6) The broadcast band of wavelengths (hitherto 
from 350 to 425 meters) to be increased so as to 
include wavelengths between 300 and 500 meters 
(except those from 440 to 460 meters which are used 
for maritime purposes. 

(7) The Broadcasting Company's license to be 
extended from the end of 1924 to the end of 1926, 
but the Government to keep its hands free to grant 
additional licenses if considered desirable. 

The Committee paid a well deserved tribute 
to the excellent service provided by the Broad- 
casting Company a tribute which, when the 
Report was published, was generally echoed 
by the press. 

SOLVING A DIFFICULT PROBLEM 

WHEN the then Postmaster General, Sir 
Laming Worthington-Evans, received 
the Report in August, 1923, he immediately 
initiated further negotiations with the Broad- 
casting Company. He found the Company, 
as might have been expected, unwilling to 
accept the Report as it stood, in view of their 
strong legal position. They met him, how- 
ever, in a very reasonable spirit and a com- 
promise was arranged without serious diffi- 
culty. This compromise had been tentatively 
suggested while the Committee was sitting, 
and both parties, as well as the public, were 
well satisfied with it. Under this compromise, 
which was announced about the beginning of 
October, 1923, it was agreed that up to the end 
of that month a special form of license, known 
as the "interim license," should be issued 
in order to "whitewash" the many unlicensed 
receiving sets which, it was believed, had come 
into existence during the period of the dead- 
lock. The fee for this "interim license" was 
to be 155. a year, out of which the Broad- 
casting Company was to receive \2s.6d. In 
addition to this form of license, the broad- 
cast receiving license at ios., applicable only 
to apparatus bearing the B. B. C. mark, was 
continue to be issued; and a constructor's 
license at 155. was to be introduced, applicable 
to apparatus made or put together by or on 
behalf of the licensee himself. The only 



special condition of this license was to be an 
undertaking by the licensee not intentionally 
to use, in the construction of his set, material 
or parts made elsewhere than in Great Britain. 

ONE MILLION TWO HUNDRED THOUSAND RE- 
CEIVER LICENSES IN ENGLAND 

THERE was immediately a very large 
demand for the "interim license," and 
some 200,000 of these were issued up to the 
end of October. The constructor's license 
also proved popular, being issued in the pro- 
portion of about two to one B. B. C. license. 
The total number of licenses continued to 
grow at a rapid rate, and by the end of the 
year it had reached about 500,000. Each 
month of the new year also saw a rapid growth, 




THE MASTS OF THE NEW BRITISH STATION 
Which will soon be opened at Daventry. This 
station will use 1600 meters and about 25 kilowatts 
and will originate programs of its own as well as 
broadcasting programs from the main London studio 
of the British Broadcasting Company. The site 
of the station is 600 feet above sea level and the 
ground itself is about 300 feet above the surrounding 
territory. The two masts are 500 feet high and 800 
feet apart 



i8o 



Radio Broadcast 



although there was some falling off during the 
summer months. By October, 1924, the total 
had practically reached 1,000,000 and at the 
time of writing (February, 1925,) it is 1,200,000. 
In the new arrangements with the Broad- 
casting Company, the Postmaster General 
had reserved the right to issue on January ist, 
1925, the simple and uniform license (at los.) 
which had been recommended by the Broad- 
casting Committee. In view of the fact that 




; THE CHELMSFORD MAST 

Of the experimental station jxx of the British Broadcasting Company. The usual 
broadcast wavelengths of the various English stations are much the same as in this 
country, but jxx uses a 1600 meter wavelength and a power of about 25 kilowatts. 
The Broadcasting Company engineers were testing with this station the possibilities 
of using a high powered station, located at a central point, broadcasting programs 
to be picked up anywhere in England with a crystal receiver 



this further reform was drawing near, and 
that there would be difficulty in inducing the 
public to pay 15$. for the constructor's 
license in the autumn of 1924 instead of wait- 
ing until the beginning of 1925 to secure a 
license for ios., the Broadcasting Company 
agreed to introduce this further reform at an 
earlier date. The growth in the number of 
licenses, and consequently in their revenue, 
had put them in a good financial position; 

and they accord- 
ingly agreed that 
the ios. license 
should be issued 
as from July ist, 
1924. The condi- 
tion about British 
manufacture was 
to be retained until 
the end of the year. 
This reduction in 
the license fee no 
doubt assisted in 
the growth in the 
number of licenses 
above referred to. 
On and from Jan- 
uary ist, 1925, a 
simple form of 
license (at ios.), 
without any re- 
striction as to the 
country of origin 
of the licensed ap- 
paratus, has been 
in existence. 

Meanwhile, with 
the increase in rev- 
enue, the Broad- 
casting Company 
had been able to 
maintain a very 
efficient service at 
their original sta- 
tions, and they also 
had been able to 
erect a number of 
additional stations. 
These, for the most 
part, have been so- 
c ailed relay sta- 
tions, with a power 
of from 100 to 200 
watts. A more in- 
teresting develop- 
ment, however, has 
been the use, ex- 
perimentally, of 



The Story of Broadcasting in England 



181 



a much higher-powered station. For this 
experimental work a 2O-kilowatt station of 
the Marconi Company at Chelmsford has 
been used, and the effect of its use upon other 
services has been closely watched by the . 
government experts, in order to see whether 
undue interference was likely to be caused. 
On the whole the results were satisfactory; 
and the Company was accordingly given per- 
mission to erect a permanent station at 
Daventry (near the center of England). 
This station is now nearing completion. It 
will use a wavelength of 1600 meters and will 
broadcast an independent program, which 
will be transmitted from London by means of 
the ordinary telephone circuits and then re- 
layed. This station will, it is expected, 
enable programs to be received by a simple 
crystal set within a radius of about 100 miles, 
as compared with the crystal radius of about 
ten or fifteen miles which is covered by the ex- 
isting main stations of the Company, and the 
crystal radius of four or five miles which is 
covered by the relay stations. It is possible 
that the Company may wish to erect similar 
high-powered stations in other parts of the 



country, with the object of bringing practi- 
cally the whole population within crystal 
radius. 

THE BRITISH LICENSING SCHEME IS WORKING 

SINCE the revised scheme of licensing 
was brought into operation in October, 
1923, the arrangements have worked with 
remarkable smoothness and success. Those 
who have been concerned with them flatter 
themselves that the arrangements have re- 
sulted in what is probably, on the whole, the 
most satisfactory and efficient broadcasting 
service in the world. It is, of course, ex- 
tremely doubtful whether the same arrange- 
ments could have been adopted in the United 
States, where no attempt has ever been made 
to introduce a licensing system for receiving 
sets. Where the public have once got into the 
habit of installing receiving sets without let 
or hindrance it would be a very difficult mat- 
ter to induce them to accept licenses and to 
pay a licensing fee. Hence, I do not for a 
moment suggest that the system which has 
been applied in Great Britain would be suit- 
able for the United States. But here, where 




APPARATUS AT THE GLASGOW STATION 

Of the British Broadcasting Company. Many of the switches in the 
foreground are for controlling the wire lines between the various stations 



1 82 



Radio Broadcast 



the licensing habit is already in existence, it 
has proved a very simple and efficient method 
of collecting funds for the purpose of the 
broadcasting service a matter which, 1 
understand, is likely eventually to result in a 
rather difficult problem in America. No 
doubt there is some amount of evasion in 
Great Britain; how much evasion, there is 
no means of saying: but that the evasion runs 
to the lengths which some suggest is quite 
improbable. The figures, in fact, speak for 
themselves. There are 1,200,000 licenses in 
existence at the present moment. The same 
ratio of licenses to population would give a 
total of nearly 4,000,000 licenses if the popula- 
tion of Great Britain were as large as that of 
the United States. Of course, no one knows 
how many households have receiving sets in 
the United States; but I think the most au- 
thoritative estimates place the number at 
between 5,000,000 and 6,000,000. Bearing 
in mind the greater prevalence of the telephone 
habit in the United States than in Great 
Britain, one may reasonably assume that the 
habit of broadcast reception is also more 
widely spread in the States than here. And 
taking these factors into account, one may 
safely conclude that the great majority of 
listeners in Great Britain and Ireland have 
taken out licenses. 

But of late a source of difficulty has arisen. 
Hypercritical persons have been examining the 
Wireless Telegraphy Act of 1904, upon which 
the whole system of licensing is based, and 



have raised the question whether it really 
applies to receiving sets at all, as distinct from 
sending sets. I am not a lawyer, but 1 know 
the opinion of lawyers who are well qualified 
to judge; and, personally, 1 have no doubt in 
the matter at all. The question, however, 
has never been referred to a Court of Law, so 
that there is no authoritative decision on the 
subject; and the Postmaster General, rather 
than risk an adverse decision, has decided 
that no proceedings shall be taken against any 
person who fails to take out a license for a 
receiving set, until the point has been placed 
beyond the shadow of doubt by means of new 
legislation which he has recently introduced in 
the House of Commons. This decision has 
no doubt resulted in some decrease in the 
number of licenses taken out; but one is in- 
clined to believe that the great majority of 
the public are disposed to play fair in this 
matter and, irrespective of the Postmaster 
General's decision, to contribute their quota 
to the expenses of the broadcast programs to 
which they listen. The new Bill, besides 
setting this point at rest, imposes a number of 
new provisions in regard to licensing which do 
not in particular apply to broadcasting: and, 
as I write, it is arousing a good deal of criticism 
in Parliament and the press. What will be 
its fate does not yet appear; but the system 
of licensing in connection with the broadcast- 
ing arrangements has proved so convenient 
and popular that one cannot imagine that 
Parliament will scrap it. 




ENGLISH BROADCASTING APPARATUS 

Is not very different from that used by most American stations. One of the 
British stations, indeed, uses apparatus manufactured by an American company 




THE U. S. S. SHENANDOAH 

During the recent transcontinental trip of the Shenandoah, the Naval radio operators aboard the ship were 
in constant communication through their short wave transmission with radio amateurs in all parts of the 
country, as well as with the Naval Laboratory at Belleview, near Washington. A wavelength of 80 meters 
was used. The cooperation extended by the amateurs in this instance was one of many examples of a 

similar sort 



New Paths for the Short Waves 

Details of the Great Contributions Made by the American Radio 
Amateur to Radio Transmitting Knowledge How the Amateurs Are 
Cooperating With the Navy A New Theory for Radio Transmission 

BY KENNETH BOLLES 



THE first congress of the International 
Amateur Radio Union which was held 
in Paris, April 14 to 19, with many 
delegates present speaking a great 
variety of languages, is really the first practi- 
cal indication that amateur radio is destined 
to become an efficient and orderly world force. 
It has taken hardly two years for amateur 
radio to grow from a localized activity, chiefly 
confined to the United States, to an inter- 
national relay system with far reaching in- 
fluence. It must have its regulations and 
understandings in order that equal freedom 
and fair play may be given to those who de- 
sire to participate in its activities. The 



congress is the first official step in making such 
provisions. 

Amateur radio, under the guidance of the 
American Radio Relay League, has trained 
some 20,000 young men in the principles of 
radio science and in a knowledge of the code. 
Those who refer to it as purely a sport reckon 
without a true appreciation of its influence 
in the development of commercial radio and 
broadcasting. Hiram Percy Maxim, and Ken- 
neth B. Warner, president, and secretary of 
the A. R. R. L., respectively, and delegates 
to the I. A. R. U., said upon leaving, that they 
believed international friendships by radio 
would be a factor in bringing world peace. 



1 84 



Radio Broadcast 



They said that in all countries, where ama- 
teurs are found, hope may be held for swift 
progress in all lines of radio science. 

The progress of amateur radio is already 
being realized by governments of various 
countries where amateurs are active. The 
1. A. R. U. may crystalize the opinion of 
amateurs all over the world for the benefit of 
those countries which 
desire technical guid- 
ance in drawing up 
regulations governing 
private international 
communication. The 
desire of amateurs to 
gain the utmost free- 
dom is no stronger 
than their wish to 
turn over to the radio 
public the results of 
their deductions and 
experiments. 

What have the am- 
ateurs done to war- 
rant any sort of world- 
wide recognition? 
What practical thing 
have they accom- 
plished that would 
justify giving them 
greater freedom? 
Almost everyone is 
familiar with their 
message handling 
during emergencies, 
their cooperation 
with the American 
Railway Association, 
their assistance to the 
Navy Department 
during the transcon- 
tinental trip of the 
Shenandoab , but 
these are outside of 
their established rou- 
tine and are not as 

convincing as those things which are a last- 
ing and permanent benefit to radio develop- 
ment. 

WHAT HAVE THE AMATEURS DONE? 

THE one great outstanding contribution of 
amateurs to .the radio art is their de- 
velopment of the short waves. They have 
gone farther in this field than any other group. 
They have proved short waves are of unsus- 
pected importance. The various radio groups 
have become interested in these bands be- 



A Record of Accomplishment 

HpHE American Radio Relay League is 
* one of the unique organizations in Amer- 
ica a land of many organizations. It was 
founded a little over ten years ago to band 
together amateur radio telegraph experimen- 
ters whose activities were largely concerned 
with exchanging private messages with one 
another over comparatively short distances. 
Now, more than 15,000 experimenters are 
members and the exchange of messages is but 
a small part of their activities. Perhaps the 
field in which they have aroused most interest 
is in their experiments with very short radio 
waves. Every reader of newspapers knows 
that the only link that Donald MacMillan had 
with the outside world when he made the 
recent trip of exploration in the Arctic was 
that forged by amateur radio communication. 
The Department of Commerce recently re- 
cognized the excellent development work the 
radio amateurs were doing with short waves 
by granting them a band of waves between 
.7496 and .7477 meter. The present article 
describes some of the activities of the Amer- 
ican Radio Relay League and tells particu- 
larly of the work of two of their most prom- 
inent members, John L. Reinartz, and F. H. 
Schnell. The work of these earnest amateurs 
is reflected in their excellent and authorita- 
tive publication, Q S T, and the Navy De- 
partment has shown its confidence in their 
earnestness by arranging to have Mr. Schnell, 
Traffic Manager of the League, accompany 
the Pacific fleet on its manoeuvres this sum- 
mer. THE EDITOR 



cause of the pioneer work that has been done 
by amateurs. 

With these short bands given over to their 
exclusive use, amateurs in this country have 
demonstrated they can send their signals 
to any part of the world where there are radio 
fans and radio receivers to pick them up. It 
has become practically impossible to name 
any country in the 
world where local 
amateurs are at all 
active that has not 
heardAmerican ama- 
teurs calling. 

The signals of oper- 
ators on the west 
coast of this country 
are being heard regu- 
larly in South Amer- 
ica and over sim- 
ilar distances, 
almost with as much 
ease as European and 
American amateurs 
could communicate 
with one another a 
year ago. English 
and New Zealand 
"brasspounders" 
demonstrate their 
superior skill by com- 
municating with the 
Antipodes. Barthol- 
omew Molinariof San 
Francisco, winner of 
the Hoover amateur 
efficiency cup for 
1924, reports that his 
signals ha've been 
heard in the following 
lands and islands: 
France, England, 
Italy, Chile, Argen- 
tina, Cuba, Panama, 
Tahiti, Tonga, Sa- 
moa, Pribiloff Is- 
lands, Tasmania, Korea, China, British India, 
South Africa, Philippine Islands, Malay 
Straits Settlements, on ships off Cape Horn 
and off the coasts of Borneo, Guatemala, 
Honduras, Nicaragua and Costa Rica, and 
the Republic of Salvador. 

The assumption upon reading this and many 
other similar records, is that short waves and 
low power are as capable of covering as great 
distances as long waves and high power at aj 
cost that is astonishingly less. 

That the development of short waves has < 



New Paths for the Short Waves 



by no means been exhausted was demon- 
strated recently by two important events, 
one of these being the decision of the Navy 
Department to seek the cooperation of Ameri- 
can Radio Relay League amateurs in an 
investigation of short waves during manoeu- 
vers of the Pacific Fleet this summer; the 
other, the announcement of John L. Reinartz's 
theory of daylight transmission. 

WHAT THE AMATEURS ARE DOING 

IN ORDER to carry out the navy experi- 
ments successfully, F. H. Schnell, traffic 
manager of the American Radio Relay League 
who has been given a seven months' leave of 
absence by the League, will conduct tests with 
amateurs in many countries. His work will 
serve as one more important link between 
American amateurs and transmitting opera- 
tors in other parts of the world, and he will, at 
the same time, demonstrate under official 
supervision what short waves can do. His 
experience as traffic manager of the A. R. R. L. 
has given him a wide acquaintance among am- 
ateurs which the Navy believed would be of 
great service in the short wave tests and so it 
called him in active service in the Depart- 
ment with the rank of lieutenant. 

It is significant that following closely upon 
the first international amateur congress, the 



U. S. S. Seattle is now steaming in Pacific 
waters equipped, among other apparatus, with 
a typical amateur radio transmitter and re- 
ceiver. This first amateur type station to 
be installed on a Navy ship will have the call 
NRRL. One may imagine the interest and 
enthusiasm in which amateurs in Australasia, 
the Philippine Islands, China, Japan, South 
America, and probably Europe and Africa 
will listen for this special Navy station, pleased 
with the thought that the communication 
they have helped to build has been recognized 
by the United States Navy. 

THE y. s. s. "SEATTLE" EXPERIMENTS 

THE amateurs who intend to listen for 
NRRL, no matter whether they are located 
in this or foreign countries, must be prepared 
to tune-in on a number of different wave- 
lengths, for the tests are to cover several bands 
of short waves. At night, the main set at 
NRRL will transmit on 54.4 meters while in 
daylight it will shift to 27.2 meters. There 
will also be transmitters functioning on 20, 
40, and 80 meters. 

If it is found that the low power amateur 
stations employing less than one kilowatt are 
just as efficient as regards the distance cov- 
ered and dependability of operation, it may 
be seen very readily that their use would mean 




JOHN L. REINARTZ 

Of South Manchester, Connecticut. Mr. Reinartz, using a wavelength of 21 meters and low power 

recently established communication with an amateur on the Pacific coast at noon. This remarkable feat 

showed strikingly the possibilities of short wave radio work 



1 86 



Radio Broadcast 




LIEUTENANT F. H. SCHNELL 

Traffic manager of the American Radio Relay 
League. Mr. Schnell has been commissioned a 
Lieutenant in the Navy, assigned to the fleet on its 
Pacific cruise this summer. He will experiment 
with short radio waves and communicate with 
transmitting amateurs all over the world. The 
American Radio Relay League has about 20,000 
members, excellently organized for intercommunica- 
tion by radio. Members of the organization have 
communicated great distances using short wave- 
lengths and very low power 

a tremendous saving in the cost of the initial 
radio installation. The average amateur 
transmitter can be put together for about 
$250. while the high power navy set may 
average somewhere around $6000. It is 
even possible that if the tests made by NRRL 



are quite successful, we may see the Navy 
changing to low wave sets in preference to 
the longer wave, high power transmitters 
they are now using. 

The reader should not interpret from this 
that the Navy is just now beginning to show 
an interest in the short waves, for it has been 
working hand in hand with amateurs for some 
time. Some of the most important experi- 
ments ever made in connection with low power 
transmission have been undertaken through 
correct cooperation between the Navy and 
amateur operators. The Navy has been us- 
ing short wave transmitters on certain ships 
for many months and as long as two years 
ago, the short wave station of the U. S. S. 
Oloio was heard on the west coast. 

The theory of daylight transmission pre- 
viously mentioned in this article was a direct 
result of tests conducted by John L. Reinartz 
at South Manchester, Connecticut, and Dr. 
A. H. Taylor of the Naval Research Labora- 
tory at Bellevue, Washington, D. C. The 
experiments which they started a year ago 
are still in progress. As a result Reinartz 
has demonstrated repeatedly that with a 
low powered transmitter using 2 1 meters, great 
distances can be covered in daylight. While 
transmitting from his station at South Man- 
chester, Connecticut, about noon, Eastern 
Standard Time, his signals have been heard 
by amateurs on the west coast, in Florida, 
and in England, and he has several times con- 
ducted two-way communication direct with 
the Pacific coast at noon. 

This gave definite proof that the very 
short waves travel farther in the daytime 
than they do at night, which is the reverse of 
what has already been known, that the long 




THE 2OO WATT TUBE TRANSMITTER 

For use on very short waves which Mr. Schnell will use for experimental communi- 
cation while he accompanies the Navy fleet on its Pacific cruise this summer 



i8 7 




THE U. S. S. SEATTLE 

Where Mr. Schnell will make his headquarters during his short wave tests. The Navy has shown great 
interest in the possibilities of short wave communication and is cooperating with the American radio ama- 
teurs who have contributed a great deal to the development of this transmission. At present, Naval com- 
munication is carried on chiefly by long wave high power radio transmitters, which are not only expensive, 
but subject to the familiar effects of daylight fading 



waves could cover great distances at night, but 
were unable to travel very far under daylight 
conditions. Until then, it was thought the ion- 
ization of the atmosphere caused by the sun's 
rays had practically the same unfortunate ef- 
fect on all waves and that daylight might be 
always a big hindrance to radio transmission. 

THE EFFICIENCY OF SHORT WAVES 

IN ADDITION to making the bare discovery, 
Mr. Reinartz developed a theory which ap- 
pears to explain the phenomenon satisfactorily. 
It is based on the well known fact that radio 
waves are reflected by the atmosphere in the 
same manner that light rays are reflected 
with the aid of a polished surface. The dis- 
tance that radio waves will travel in daylight 
is determined by the length of the wave, for 
it appears it is this factor which controls the 
height at which the reflection takes place. 

There is a definite relationship which con- 
nects the position and effect of the sun with 
the length of the radio wave and the distance 
that it will be reflected. The depth of the 
reflecting layer varies with the time of day 
and season. The shorter waves seemingly 
have the peculiar faculty of penetrating 
farther into the ionization layer and they are 
therefore capable of being reflected to a much 
greater distance. 



"The fact that the shorter wave penetrates 
the ionization layer to a greater height," 
declares Mr. Reinartz, "causes the reflection to 
take place at a higher altitude than would be 
the case for the longer; therefore, the diameter 
of the circle at which the short wave again 
appears on the earth's surface is larger. 
Inside of this circle there is no evidence of 
the radio wave until one gets very close to the 
transmitting station. The reason for this 
is that the waves which travel along the 
earth's surface have been subjected to all the 
absorbing influence which that surface car- 
ries, while those which went up to the ionized 
layer and were reflected back have traveled 
through a considerable space and very little 
energy has been lost. This makes it possible 
to cover tremendous distances with but a 
fraction of the energy needed for some of the 
longer waves. 

"It is possible to use this information in 
such a way as to obtain reliable daylight 
ranges considerably in excess of reliable night 
ranges obtainable with the same power." 

Mr. Reinartz makes the prediction that this 
year will see communication established be- 
tween amateurs of the United States and Aus- 
tralasia on a wavelength of about 20 meters 
in broad daylight. Mr. Reinartz will have an 
intensely interesting opportunity to test his 



1 88 



Radio Broadcast 



theory when he leaves as operator on Donald 
MacMillan's Bowdoin on June i5th of this 
year. Extensive experiments are to be carried 
on with daylight transmission on 20 meters 
while the ship is in polar waters. Mr. Rein- 
artz as operator, has been appointed to the 
place held by Donald Mix aboard this ship 
on the previous voyage. Mr. Mix is also 
a member of the American Radio Relay 
League. 

Both those appointments show beyond 
question the value placed on amateur talents. 

For a number of years American amateurs 
worked with all of their might to send their 
signals across the Atlantic ocean. Their final 
success marked the real beginning of inter- 
national amateur communication for it was 
not until that time that the future possibilities 
of low power and short waves were fully real- 
ized. Their next task was so to perfect their 
instruments and method of operation that 



they could exchange messages at will with 
private individuals in various foreign coun- 
tries. 

Immediately that two-way communication 
was established between amateurs on oppo- 
site sides of the ocean, interest of operators 
in this country reached a high state of en- 
thusiasm and amateurs began to spring up 
here and there in countries where they had 
never been heard of before, until now they 
may be found dotting almost every part of 
the world. Three or four years ago American 
amateurs kept before them constantly a wall 
map of the United States, while now in these 
same radio shacks may be found world maps 
and globes. 

With one kilowatt of power and a barrel 
of enthusiasm, amateurs threaten to conquer 
the three obstacles to radio communication, 
time, space, and daylight, using short waves 
that once nobody thought were of value. 




THE WINNER OF THE HOOVER CUP FOR 1924 

Bartholomew Molinari, owner of amateur radio station 6 AWT, San Francisco. The transmitter is one 250- 

watt tube, shown on the panel in the lower left. Note the wall map of the world, dotted with colored pins, 

showing the various parts of the world in which 6 AWT has been heard. Ten years ago, distance records 

such as these would have been considered an absolute impossibility 



Making Radio Receivers More 

Selective 

Practical Instructions on How to Improve the Selectivity of Various Popular 
Circuits in Use A Clear Explanation of the Theory Involved in the Changes 



BY KEITH HENNEY 



THE problem that has been bothering many radio listeners recently, is one of 
the selectivity of their receivers. Mr. Henney, in this article, has discussed 
the whole question of selectivity. There is such a variety of circuits and sets to 
be considered when one tries to solve the problem of increasing the sharpness of 
tuning that a general consideration such as this, we think is the best way to help 
the individual. This is distinctly not a how-to-make-it article, but the reader will 
find all the necessary constructional information given. The individual can apply 
this information to suit his own problem. The suggestions here given are more in 
the nature of a remedy than a cure. The real cure for the situation lies in a re- 
adjustment of the broadcast transmitting situation. We believe that Mr. Henney's 
discussion of the theory involved here will prove very helpful to the radio con- 
structor. THE EDITOR 



ACCORDING to the average radio 
listener, the flaws in the present 
scheme of broadcasting are two: the 
multiplicity of stations and the ap- 
proach of "super-power." And in his pecu- 
liar dilemma of wanting to be in touch with 
all that goes on in the ether and yet to be 
exclusive, the listener must turn in but one 
direction, to increased selectivity. 

Whether the problem is to doctor a receiver 
now in operation or to build a set that will be 
sufficiently selective, the questions that face 
the radio listener are the same: 
What is selectivity? 
How may it be obtained? 
How much is necessary, or desirable? 

WHAT IS SELECTIVITY? 

CELECTIV1TY is a relative term, and 
^ signifies the ability of a receiver to dis- 
tinguish between several transmitting stations 
operating on frequencies that do not differ 
much from one another. To take an analogy 
from the phonograph field, let us suppose 
that the mechanism for recording music would 
respond only to those tones that lie between 
middle C and one octave above. Then no 
matter how many notes a pianist might play, 
the mechanism would record only those be- 
tween the proper limits. In other words, the 



recording apparatus would be selective, and 
other tones would not bother it. 

Broadcasting stations in Class B are now 
stationed 10,000 cycles apart. A receiver 
sufficiently selective will, respond to only one 
station at a time. Frequencies 10,000 cycles 
different from that to which the receiver is 
tuned will not be heard to any marked degree. 



799 800 801 KILOCYCLES 




799 800 801 
FREQUENCY IN KILOCYCLES 

FIG. I 

The current in a receiving circuit increases as the 
resonance point is reached, as shown in this Figure. 
This receiver would be too sharp since it will respond 
to a band of frequencies only two kilocycles wide 
and would lose the higher musical notes entirely. 
A good receiver should have a resonance curve 10 
kilocycles wide in order to get all of the notes broad- 
cast from the transmitter 



190 



Radio Broadcast 




FIG. 2 

This is the typical "blooper" circuit in which the 
antenna is closely coupled. This close coupling 
brings in the signals, but when the tube oscillates, 
it sends out signals as well much to the discomfort 
of all near-by listeners 



Fig. i is a resonance curve of a receiving 
set that will respond to a band 10,000 cycles 
wide. 

Such is the ideally selective receiver. 

How may it be obtained? 

There is but one cause of poor selectivity 



resistance, and the remedy is obvious: eli- 
minate that resistance. This task, however, 
of separating the various resistances from a 
receiver reminds one of the adage of cutting 
off one's nose to spite one's face, for to remove 
all of the resistance would be to remove the 
receiver itself. 

For the listener who builds his own receiv- 
ing set, resistance is added through the use of 
long connections, poor coils and condensers, 
by placing coils too near large masses of 
metal, poor contacts, or by closely coupling a 
low resistance circuit to one in which consider- 
able resistance exists. 

The listener who owns a manufactured set 
must place his faith in the engineer who de- 
signed it and the factory that made it. There 
is little that can be done to the inner "works" 
that will better its tuning qualities. That 
little will be described in this article as well 
as the tricks that can be performed external 
to the receiver itself. 

TO IMPROVE SELECTIVITY 

THERE are two general methods of im- 
proving selectivity. The first strikes at 
the cause, resistance. The second relies upon 
tricks such as placing obstacles in the path of 
unwanted signals, or of filtering out those 
that are desired and letting the others go 
where they will. In the latter method lie 




RADIO BROADCAST Photograph 



FIG. 3 

A photograph of a single-circuit receiver in which the antenna is not actually connected to the detector but 

through another coil closely coupled to it. One stage of audio frequency amplification has been added. 

This is the nucleus of a good receiver such as shown in the photograph in Fig. 4 



Making Radio Receivers More Selective 



191 




RADIO BROADCAST Photograph 



FIG. 4 



Here is a complete receiver built around the single-circuit blooper. The coil and condenser to the left com- 
pose the essentials of a radio-frequency amplifier, the second coil is the detector secondary and the amplifier 
plate coil coupled to it. The third condenser is for introducing regeneration in the detector. There are five 
tubes, three producing audio frequency amplification. The Pyrex socket is a good one for radio amplifiers 

due to its low losses 



the wave traps and radio-frequency ampli- 
fier circuits. 

In other words, we may eliminate the cause 
of poor selectivity and there is a certain 
limit beyond which we cannot go in this di- 
rection or we may force signals to go through 
a kind of maze through which those that are 
desired will emerge and in which the others 
will be lost. 

IMPROVING THE SINGLE CIRCUIT RECEIVER 

IT IS in the realm of the simple receivers, 
the bloopers and any set that employs no 
radio frequency amplification that the most 
can be done to sharpen the tuning. In Fig. 2 
is the typical blooper circuit with its antenna 
closely coupled to the remainder of the cir- 
cuit a condition that broadens the tuning, 
and sends out into the ether the parasitic 
signals that condemn this type of receiver. 
Fig. 3 shows how simply such a receiver may 
be made and provided with one stage of audio 
frequency amplification. 

The use of regeneration is a method of re- 
ducing an already existent resistance, and the 
ability of this simple receiver to go out and 
get distance lies in this resistance reduction 
the same phenomenon that makes it a nui- 
sance to all near-by listeners. An oscillating 
receiver is without doubt the most sensitive 
and selective, but its very sensitivity makes it 



unhandy. Small changes in the antenna sys- 
tem cause the oscillating frequency to vary 
with accompanying distortion. 

The best possible addition to make to a 
blooper is a single stage of radio frequency 
amplification, an addition that increases its 
range, its volume, and its selectivity as well 
as eliminating its liability toward radiation. 
Fig. 4 represents such a circuit, together with 
appropriate audio amplifiers. The coils 
should be far apart and at right angles to 
each other, so that proper neutralization may 
take place. The photograph shows how 
simply such an amplifier can be made and 
clearly illustrates the proper placing of coils. 

The amplifier plate coil may be made by 
winding ten or fifteen turns around the middle 
of the blooper secondary that is now used, 
forming the connection between the amplifier 
and the detector. The coupling between the 
antenna and secondary of the radio-frequency 
amplifier should be as loose as is consistent 
with good signal strength, and the same may 
be said of the coupling existing between the 
plate coil and the detector secondary. In Fig. 5 
is shown the effect of close coupling, which 
is one of the best methods of adding resis- 
tance to a circuit and ruining its selectivity. 

The effect of retaining regeneration in the 
detector is shown in Fig. 6 where the re- 
sonance curve becomes sharper and sharper 



192 



Radio Broadcast 




**-Uow Resistance Circuits'' 
RADIO FREQUENCY AMPLIFIER 

FIG. 5 

Whenever a circuit of low resistance is closely 
coupled to a circuit of high resistance, it tunes 
broadly. In other words some of the high resis- 
tance has been "reflected" into the low resistance. 
The solution to this trouble lies in separating the 
two coils as far as is consistent with signal strength 



10 



<-> i 

Ul * 

ce 





_-J 10,000 



,-'5000 



1000 



INCREASING TICKLER COUPLING 



FIG. 6 

According to most authorities, regeneration is a means of reducing the 
resistance in a circuit. It is accompanied by sharp tuning, and the 
more regeneration that is used, the narrower is the frequency band taken 
in by the circuit. Near the oscillation point, the circuit may become 
so sharp that "side bands" are chopped off and poor quality results 




FIG. 7 

A coil and a condenser are the requisites of an obstacle to put in the 
path of a radio frequency current. Such a device, if properly used, 
may sharpen the tuning because it must be accurately tuned before any 
energy can get through. Two or more increase the selectivity because 
nothing gets through until each obstacle is tuned correctly 



with the result that near the oscillation point, 
the quality goes bad. 

With the addition of such an amplifier to 
a blooper, the listener now has the advantage 
of decreased resistance due to regeneration 
but the added feature of a wave trap in the 
antenna circuit. All signals must pass the 
tuned circuit consisting of a coil and a con- 
denser before they can get to the detector, 
and before that happens they must also pass 
through the vacuum tube which boosts their 
voltage by at least six times. The wave trap 
sharpens the tuning and additional tuned 
circuits may increase still further the nar- 
rowness of the received frequency band, 
but the trap itself does not add voltage; 
this is the function of the tube. These facts 
are shown in Figs. 7 and 8. 

WAVE TRAPS 



TF THE listener does not 
* care to add anothertube, 
or if he already possesses a 
stage or two of radio fre- 
quency amplification, he 
may use the coil and con- 
denser of Fig. 3 as a "wave 
trap," and provided that 
they be of low resistance, 
he will be able to cut his 
path through interference 
with greater ease. 

Wave traps, in general, 
are of two kinds: those that 
are shunted across the an- 
tenna and ground and 
called "acceptors," and 
those that are in series with 
the antenna and ground 
which are called "rejec- 
tors." A rejector prevents 
one frequency from getting 
into the receiver, but lets 
all others pass; in other 
words, it cuts a slice out of 
the stations that are on 
the air. An acceptor pro- 
vides a convenient by-pass 
for all frequencies but the 
one that the listener de- 
sires to hear. 

The wave trap is simply 
a good coil and a good 
condenser connected and 
placed in some part of the 
antenna - ground system. 
The trap used in RADIO 
BROADCAST Laboratory 



Making Radio Receivers More Selective 



\7 



1st Stage 
Radio ; 



2nd Stage 
Radio 



Detector, 



1=0=0=: 




8 

A radio-frequency amplifier not only acts as a 
trap for unwanted signals but boosts the voltage of 
the one signal desired. In this Figure, the effects 
of adding several stages of tuned amplification are 
illustrated. Each additional stage cuts down the 
width of the frequency band that is passed and in- 
creases the voltage 

and shown in Fig. 9 consists of a General 
Radio .0005 mfd. condenser, across the ter- 
minals of which is shunted a low-loss in- 
ductance coil. Around the coil were wound 
several turns of wire, and it is these turns that 
are inserted in the antenna-ground system. 
Any good coil and condenser that will cover 
the frequency range may be used. The re- 
ceiver shown in Fig. 9, then, consists of a 
single circuit blooper with a wave trap to 
sharpen the tuning and cut down interfer- 
ence and a Samson 3-1 transformer to provide 
additional volume. Fig. 10 shows in a sche- 
matic manner the connections of a wave trap. 
Various methods of connecting the trap to 
a receiver now in use are shown in Fig. 1 1 . 
When in series with the antenna, as in A or C, 
they may be set at the wavelength of some in- 
terfering station. That station will not in- 



terrupt until the tuning of the trap has been 
changed. When across the input to the 
receiver, as in B or D, a trap will let into the 
set only the signal that is desired, and make 
tuning somewhat more complicated. On the 
other hand, once the listener becomes accus- 
tomed to the tuning, he will find this type of 
considerable value. 

Two traps may be used, one tuned to some 
particular station and thereby eliminating its 
signals, and the other adjusted along with 
the tuning of the receiver itself, as is illus- 
trated in E, Fig. 1 1. 

A wave trap will not increase signal strength; 
it will work well only with a receiver in which 
the antenna circuit is completely or partially 
tuned; it will perform its duties only if low 



O Q Q Q Q Q Q 






































FIG. IO 

The connections of the wave trap shown in Fig. 9 

The coils and condensers in such a device should 

be of low resistance to make the tuning sharp 




graph 



FIG. 9 

A simple wave trap consisting of a coil shunted by a condenser is inserted in the antenna circuit by means of 
several turns of wire wound around the coil. This is then a "rejector" since it rejects one frequency that 

is unwanted 



194 



Radio Broadcast 



resistance parts are used; and will not be of 
value to the more complicated receivers of 
the radio-frequency amplifier type. 

On the other hand, a wave trap will be 
a boon to the blooper, to the two-, the 
three-, and the four-circuit receivers; for 
it will cut a slice out of the ether where 
there is some interfering station, and it will 
stiffen up the tuning of the antenna circuit 
considerably. 

The coil and condenser shown in Fig. 9 may 
be calibrated in wavelengths or frequencies 
and used as a measure of incoming waves, and 
it need only be placed near one of the coils of a 
receiver, be it a blooper or a five-tube affair, 
to indicate the frequency of incoming signals. 
When the condenser is tuned, a marked de- 
crease in signals will be noted, and if it is 
used with an oscillating receiver, a sharp click 
will be noted in the phones when passing the 
frequency of the signal. 

For this purpose, the additional winding is 
not necessary and the unit then consists of 
simply a coil and a condenser, which may be 



RADIO FREQUENCY AMPLIFIER 



o 
o 

o 







FIG. 12 

A simple method of increasing selectivity is illus- 
trated in this Figure. The condenser may be var- 
iable, but after the correct place to tap the coil is 
found there is no need for further adjustment 



calibrated either in wavelengths or frequencies 
by noting where several well known broad- 
casting stations are tuned. A curve may then 
be plotted showing the relation between con- 
denser setting and wavelengths or frequencies. 





c- 




-D- 





FIG. 1 I 

Wave traps are really simple devices, consisting of a coil shunted by a condenser. But to be effective, both 
of these component parts must be of low resistance. In this Figure are shown several methods of connect- 
ing such a trap to the antenna circuit of a receiver. They are useful only if the antenna is partially or com- 
pletely tuned, and will not do much good when used with a complicated receiver. With the simple circuits, 
however, they will enable the listener to cut out unwanted stations, and to sharpen the tuning of his receiver 



Making Radio Receivers More Selective 



195 



RADIO FREQUENCY AMPLIFIER-REGENERATIVE 
DETECTOR RECEIVERS 

I N RECEIVERS such as the Roberts Knock- 
* out, the Browning-Drake, the Teledyne, 
and others of similar nature using a regenera- 
tive detector with one or more stages of radio 
frequency amplification, there are several 
things that may be done to improve the over- 
all selectivity. 

The series condenser in Fig. 12 is a potent 
device for sharpening tuning, especially since 



T 






o 


i 
* 




-A- 


o 




A 


o 


TV 


9 


B 


o 


/ 


^ g LJ^ 


i 


1 


o 


I 


iiriii 




< 


o 

o 9 


^ 


4=^ 




*""> ' 

o 




> 


-? e 







-B- 




FIG. 13 

Adding an inductance coil to the antenna circuit and 
partially tuning it by taps or completely tuning the 
circuit by a variable condenser will add to the abil- 
ity of the receiver to select the signals a listener 
wants. The coupling to the receiver may be de- 
cidedly loose if the antenna is carefully tuned by 
means of the variable condenser 

regeneration in the detector makes up for 
any loss in signal strength resulting from the 
insertion of this condenser. 

Another method was described in RADIO 
BROADCAST for April in the article on experi- 
ment with the Roberts circuit. This is the 
addition of inductance in series with the an- 
tenna and partial tuning by means of taps, or 
complete tuning by means of a variable con- 
denser. Fig. 13 illustrates both methods. 

Loose coupling between the antenna coil 
and the secondary of the amplifier and the two 
coils connecting the amplifier and detector is 
necessary for the sharpest tuning, as shown 




FIRST RADIO AMPLIFIER 







NEUTRODYNE CIRCUIT 



COOP 







FIG. 14 

The use of a loop in place of the first coil of a neutro- 
dyne presents few difficulties, especially when it is 
to be used on local stations. The loop should have 
the correct dimensions so that it will take the place 
of the neutrodyne coil that is removed. The loop 
will provide a decided increase in selectivity due to 
its directional effect, but of course will cut down 
signal strength 

in Fig. j. This feature is embodied in several 
coils now made for the Roberts receivers. 

THE NEUTRODYNE 

THE two stages of radio frequency ampli- 
fication of the neutrodyne are simply so 
many wave traps, each making the band of 




RADIO BROADCAST Photograph 
FIG. I> 

The "inner works" of a wave trap used in RADIO 

BROADCAST'S Laboratory. The conventional coil 

and condenser are well illustrated as well as a method 

of mounting them 



196 



Radio Broadcast 




RADIO BROADCAST Photograph 
FIG. l6 

The outward appearance of the wave trap illustrated 

in Fig. 15. This makes a neat-appearing addition 

to any broadcast listener's equipment 

frequencies that is finally passed into the de- 
tector, sharper. For this reason a neutrodyne 
should be very selective. There is the addi- 
tional advantage in the tuned radio fre- 
quency circuits that each vacuum tube adds 
a certain amount of amplification, so that 
there is a gain in volume as well as in select 
ivity, as shown in Fig. 8. 

The use of a small antenna is advisable if 
interference is to be cut to a minimum. If 
space is available, two antennas may be 
erected at right angles to each other and their 
directional properties used in cutting out un- 
wanted stations. 

Proper neutralization is highly important 
in those receivers using the Hazeltine scheme 
of stabilization, and in the potentiometer- 
stabilized sets, this instrument should be 
used as far as possible toward the negative 
end of its scale. 

Often the addition of slight regeneration in 
the detector circuit is helpful, but a receiver 
with two stages of high-frequency amplifica- 
tion is a bad place to add a tickler. The 
whole system is liable to howl. 

Much will be gained by the use of a loop 
instead of an antenna, or even in place of the 



first coil of a neutrodyne. This is especially 
true when there are powerful near-by broad- 
casting stations. Fig. 14 shows how the an- 
tenna loop may be substituted for the antenna 
coil and secondary of the first amplifier. 

The scheme illustrated in Fig. 1 1, in which 
a small condenser, say about .0001 mfd., is 
placed in series with the antenna, may be ap- 
plied to the neutrodyne. This tends to 
loosen the coupling with the antenna and to 
prevent its high resistance from getting into 
the amplifier. It has the disadvantage that 
it may cause somewhat weaker signals and 
change the readings on the first condenser. 

IMPROVING THE SUPER-HETERODYNE 

THERE is no receiver available to-day 
that has the potential sharpness of tuning 
of the super-heterodyne. Here is an oscillat- 
ting circuit, in itself a maximum of selectivity; 
here are two or more intermediate circuits 
through which the signals must pass before, 
being heard; here is a low-resistance energy 
collector, a loop. 

There is little that can be done with a 
"super" that is already in operation. Meth- 
ods of adding regeneration to a loop have 
been described in RADIO BROADCAST. If an 
external loop is used, the listener should make 
sure that it is of low resistance, not placed 
near any metallic objects, such as a radiator, 
or wall of a steel-lathed room or a steel build- 
ing. I f there are taps, they should make good 
contact. 

A good loop is directional, that is, it re- 
ceives better when pointed in the direction of 
the transmitting station. Full advantage 
should be taken of this tuning aid by the 
proper use of a compass fixed to the base of 
the loop. 

HOW MUCH SELECTIVITY? 

THE question finally faces the listener of 
how much selectivity is necessary or de- 
sirable. Broadcasting stations transmit into 
the ether a band of frequencies about ten 
thousand cycles wide, these frequencies being 
distributed on either side of a single sharp 
"carrier wave." Theoretically, all that is 
required for clear reception, is the carrier 
wave and one of the two "side bands," which 
would require a receiver with a resonance curve 
only five thousand cycles wide. Practically, 
it is difficult to make coils with low enough 
resistance that the resonance peak will be 
less than ten thousand cycles wide, and if 
this sharpness is secured the listener will 
have no difficulty in separating Class B sta- 



Making Radio Receivers More Selective 



197 



tions provided that they stay on their al- 
lotted frequencies. 

Regeneration decreases the width of the 
resonance curve, and when it is pushed too 
far the higher audio notes begin to drop out, 
producing considerable distortion. 

There is a scheme that might be tried on 
super-heterodynes that will bring in any sta- 
tion that happens to be transmitting with 
quality sufficient so that the announcer may 
be understood but music will be pretty 
badly distorted. This scheme consists in 
placing a band filter in the receiver passing 
only frequencies between 1,000 and 2,000 
cycles. This will make tuning so sharp that 
little interference will be experienced and 
many of the low-frequency spurts of static 
and noises will be eliminated. 



Since the voice frequencies that carry in- 
telligibility lie above 1000 cycles, such a filter 
would let through speech that could be under- 
stood, although entirely unnatural. 

The band filter is really two wave traps in 
series, one cutting off all low frequencies 
and the other cutting off the high ones. If 
their cut-off frequencies are close enough 
together they will let pass a narrow band of 
frequencies, and this band of frequencies 
can be made as wide or as narrow as is neces- 
sary to get the required selectivity. Since 
the frequencies dealt with in this double wave 
trap are audio frequencies, large coils and 
condensers are required, and the proper de- 
sign of these coils depends on measurements 
which cannot be made by the average radio 
constructor. 




nderwood & Underwood 



A WAVE TRAP IN A CABINET 

Interior view of a wave trap using a Heath radiant condenser and a coil, which can be wound by the con- 
structor. The simplicity of construction is obvious. The overall size of this cabinet is 8 x 7 x 5 inches 



HOW TO MAKE A DETECTOR AND TWO-STAGE AMPLIFIER UNIT 

REMARKABLY efficient radio-frequency amplifier unit was described 
by John B. Brennan in the May RADIO BROADCAST which has made a great 
appeal to many constructors who wanted to build such a unit using the most ad- 
vanced ideas of construction. In an early number of RADIO BROADCAST, Mr. 
Brennan will describe the construction of a detector and two-stage audio amplifier. 
The unit is quite as compact as the radio-frequency one. The general experimenter 
will find the detector-amplifier unit of excellent service in testing out intermediate 
amplifier, tuned radio frequency, and other circuits. This unit is easy to build, it 
is well made and substantial and incorporates some excellent constructional features. 




THE u. s. s "ARKANSAS" 

With her battery of big guns and radio antennas. At least seven separate antennas can be seen in tht 
picture. All the Naval radio communication is carried on in the longer wavelengths with cipher codes 
The larger ships have complete radio telephone equipment, which is chiefly used for communication be- 
tween ships over short distances 



THE MARCH OF RADIO 



B 




Past President, Institute of Radio Engineers 



Why Does Congress Refuse to Broadcast Its Proceedings? 



WE ARE wont to give ourselves 
credit for being the most modern 
and progressive of people, and 
in the same breath affirm that 
the English are the most conservative, and 
that their excessive caution not to upset the 
accepted customs and methods of procedure 
effectually prevents progress. And of all the 
conservative bodies of statesmen in the world 
we have readily granted that Parliament was 
the most striking example. 



Imagine then, introducing a new and novel 
instrumentality such as radio into the Houses 
of Parliament. Yet Prime Minister Stanley 
Baldwin announced recently that he contem- 
plated creating a committee of members of 
both Houses to consider the question of broad- 
casting the proceedings of that ancient and 
honorable body. 

Are we going to let our conservative friends 
show us the way? or shall we introduce 
radio broadcasting as a part of Congressional 



The March of Radio 



199 



procedure at once, before Parliament gets the 
"air"? It would appear from past news stories 
that many congressmen seriously object to 
having their oral activities spread out over 
the countryside where their constituents might 
be listening to their speeches. Can we sup- 
pose that the filibustering tactics, which have 
successfully blocked constructive legislation in 
the past as a result of petty partisan politics, 
could be carried out if several million healthy 
Americans were listening-in? Probably not. 
It would take more nerve than the average 
senator has, to get on his feet and read for 
hours senseless nothings for the Congressional 
Record with the idea of blocking some measure 
which millions of his listeners might want. He 
would get much worse than "Helen Marias" 
in his morning's mail, we imagine, and it would 
probably be unnecessary for Vice President 
Dawes to advocate changes in senatorial pro- 
cedure. 

We broadcast political conventions because, 



we now know, the people are intensely inter- 
ested in the methods of governmental proced- 
ure, as well as in the men chosen to run for 
office. But we might well ask: What is more 
important, to know who is chosen to run for 
office or to know what he does after he gets in? 
Assuredly the activities of Congress are of 
more importance to the average citizen than 
are the proceedings of the national conven- 
tions. Let us then broadcast the proceedings 
of our congressmen, whether they will or no. 
The nation has certainly the right to demand 
the privilege of hearing its elected representa- 
tives perform in office. Fewer words would 
be used and much more government business 
would be transacted, we venture to prophesy. 
As the most probable man to act, we appeal 
to General Dawes to father the movement. 
Were this sponsoring to occur we are sure he 
would be no longer concerned with senatorial 
procedure and that incomprehensible political 
cross-word puzzle would soon solve itself. 




RADIO EQUIPMENT FOR THE HOTEL 

Among the many hotels in the country to install radio service for guests is the Biltmore, in New York. 

ividual receivers are used with A and B supply and loud speaker all contained in one cabinet An 

: is tuning the receiver for Marion Benda (left) and Mary Mulhern, musical comedy actresses 



200 



Radio Broadcast 



When Radio Aided Politics 

THE service of radio to the public has 
been frequently analyzed and generally 
much over-estimated. The number of 
radio listeners is generally given as several 
million more than it is, with the idea of lending 
color to the news. Without exaggeration, 
however, it may now be stated that radio has 
really helped millions in at least one state. 
This help was not only in culture and enter- 



tainment, bat it can be measured in real dollars 
and cents. 

Governor Smith of New York State was ac- 
tively working for the passage of an income tax 
reduction of 25 per cent., but the majority of 
his legislators, being of different political faith, 
were doing their best to thwart his plans. 
Probably had they thought at all (which is 
questionable) they would have been in favor 
of tax reduction themselves, if the reduction 
could have been pointed out as a Republican 
measure. But never must 
a Democrat be allowed to 
get credit for such a uni- 
versally desired piece of 
legislation. So the tax 
measure seemed well on the 
way to be defeated by petty 
politics. From the Republi- 
can point of view this 
probably seemed a happy 
idea, for since they were 
in the majority, they could 
control the distribution of 




THE S. Y. ARA 

Owned by William K. Vanderbilt. The ship is lying in the Hudson River, off Riverside Drive with some 
apartment buildings of upper New York in the background. The radio equipment of the Ara is very com- 
plete and equals that of the largest of express liners. The interior of the radio cabin is shown in the insert. 
On the left is the \\ kilowatt c. w. transmitter, next is the radio compass equipment and then the receivers 
for long and short waves. A \\ kilowatt quenched spark damped wave transmitter and a % kilowatt emer- 
gency set complete the elaborate equipment of station KFBO. The operator is using a double speed key, 

known among operators as a "side-wheeler" 



The March of Radio 



20 1 



norrv m ri-^ 

USED \ N I92O 

aused much : TODA 

N 




EXHIBIT A FROM THE RADIO AMATEUR 

A display that speaks for itself which was one of the exhibits at the re- 
cent radio show held by the amateurs of the Second United States District 



the vast sums which the unneeded taxes would 
bring in. 

The upstate press which is largely Republi- 
can, carried very little, if any, material which 
might make their readers think well of the 
Democratic governor, and probably most of 
the voters who read those papers thought him 
an impractical visionary, but he wasn't one, 
and the petty Republican politicians soon 
discovered that even with their influenced 
press the truth could not be kept from their 
constituents. Governor Smith decided to 
talk over the radio directly to the taxpayer, 
be he Democrat or Republican. "Al" Smith 
did talk and, so effectively did he place his 
arguments before the people of New York 
State that the Republican majority were 
forced to accede to him and pass this legisla- 
tion which the people wanted. That is a real 
service which helps to weed out the petty, 
self-seeking politician and expose his actions to 
the sight of millions of those he is supposed to 
represent. Then indeed has radio the right 
to be counted as one of the important factors 
of our economic life. 

The Tangled Broadcast Situation 



T! 



kHE press recently featured interviews 
with such well-known radio men as 
Professor M. I. Pupin of Columbia 
University and Arthur Batcheller, the Super- 



visor of Radio for the Second District. 
The subject of the interviews was the ever 
increasing number of stations coming on the 
air. "We are at the end of the rope," 
says Mr. Batcheller. "The ether has reached 
the saturation point for broadcasters." Now 
if any one really knows about the situation it 
probably is Mr. Batcheller. He is the Govern- 
ment's representative in the most congested 
radio district in the world, and from morning 
to night he has to listen to radio troubles. In 
the opinion of Professor Pupin, "licenses were 
granted in the beginning without any discrim- 
ination," and we would add that such a 
policy still seems to control the issuance of 
licenses. 

A strange instance of the attitude of the 
Department of Commerce on this jamming of 
the ether was recently reported from Cincin- 
nati. Two stations in that city had been 
granted licenses to operate on the same wave- 
length, and after much squabbling as to a di- 
vision of time they finally did operate on the 
same wavelength and at the same time! It 
was reported from Washington that the De- 
partment of Commerce had been repeatedly 
asked to step in and settle this impossible sit- 
uation, but had declined on the ground that 
"to set such a precedent would get the Depart- 
ment hopelessly enmeshed in a maze of dis- 
agreements between stations." One might 
well ask the Department how it did expect 



2O2 



Radio Broadcast 



such disputes to be settled? It is a strange idea 
of privilege and duty which consents to the 
issuance of broadcasting licenses to any who 
want them and then when trouble comes to the 
listening public as a result of the excessive 
number of stations, to turn one's back and let 
someone else settle the trouble when that 
trouble was directly due to the Department's 
freedom with licenses. Who, we also again 
ask, does Mr. Hoover think will step in to 
straighten out trouble between various sta- 
tions if his department thinks the task too 
onerous? 

Let us venture again the proposition that 
licenses be refused to a new station unless the 
request is accompanied by a petition signed 
by a reasonable number of prospective lis- 
teners. The more we consider this idea the 
more it appeals to us as a sensible method of 
controlling the number of broadcasting sta- 
tions in the interest t>f the listening public. 

The Navy Establishes an Amateur 
Radio Reserve 

CAPTAIN RIDLEY McLEAN, Direc- 
tor of Naval Communications, has 
conceived the idea of increasing the 
effectiveness of the Naval Reserve Force by 
enlisting in its personnel the radio amateurs 
of the country. During the World War, much 
time and effort were spent in training a staff of 
radio operators and technicians; several 
schools had to specialize in such work because, 
at that time, there was a great demand for 
radio communication, both on sea and ashore. 
Hiram Percy Maxim, President of the Amer- 
ican Radio Relay League, has sent out a call to 
all members of his organization to file certifi- 
cates of willingness to join the Naval Reserve. 
Such enrolled amateurs will receive instruction 
in the use of Naval radio equipment, so that 
in any emergency the active radio personnel 
of the military organizations can be at once 
increased to its proper complement. It is ex- 
pected that possibly 6000 amateurs will re- 
spond to this call. We regard this move as 
an exceptionally desirable one on the part of 
the Navy. There is much talent among 
American amateurs which can be used to good 
advantage by the Navy. 

The Month in Radio 

EVERY month brings with it some pa- 
tent decision in the radio field. There 
are so many suits being waged to-day 
that it would be strange if the month did not 



record some decision or other. As to who was 
the real inventor of the regenerative circuit, 
generally credited to Armstrong, seems yet to 
be a mooted question. The fortunes of legal 
war pass back and forth, and it appears that a 
recent decision of Judge Learned Hand, having 
to do with the possibility of a suit against the 
De Forest Radio Company, shows the tide of 
battle turning in favor of the De Forest Com- 
pany. However, we cannot pretend to under- 
stand all the legal complexities and ramifica- 
tions in these patent suits, but we note, in 
passing, that neither litigant seems to have 
received a knock-out blow up to this writing. 
They are both still in the commercial running. 

IN SOME preliminary tests having to do with 
equipping army planes for summer maneu- 
vers, it was found feasible for pilots in different 
machines to converse with each other when 
they were in full flight, and as far as five 
miles apart. This seems like a very short 
distance to us who nightly hear concerts a 
thousand miles away, but it is to be remem- 
bered that the power output of the airplane 
transmitter is necessarily low and the difficulty 
of receiving is enormous because of the exces- 
sive noise caused by the powerful motors ex- 
hausting almost in one's ear and the hurricane- 
rush of the wind as the plane speeds through 
the air faster than two miles a minute. 

IS THE radio market saturated? Every time 
a temporary falling off of sales occurs, this 
question is brought up. It seems that con- 
servative estimates place the number of re- 
ceiving sets in the United States at about 
3,000,000 and on this basis we surely can guar- 
antee the radio manufacturer a fruitful market 
for some time to come. Certainly as many- 
people should own radio sets as at present 
own automobiles and phonographs and each 
of these numbers close to 1 5,000,000. Because 
of the lower cost of radio sets it would not be 
unreasonable to estimate the saturation point 
for radio receivers considerably higher than 
that for automobiles and phonographs. Our 
belief is that the market will keep on absorb- 
ing radio sets until there are about 20,000,000 
in use. 

WHEN Donald B. MacMillan departs 
again for the polar regions the latter 
part of this year his radio outfit will be pri- 
marily designed to use short waves. His 
experiences with radio during his last expedi- 
tion, as well as his recent conferences with 
radio experts here, have convinced him that 



The March of Radio 



203 



the short wave channels will prove more re- 
liable than the longer wavelengths used by 
broadcasting and commercial stations. So, 
if you want to hear news from the North Pole 
next winter, have one of your amateur friends 
build you a receiver for tuning to waves as low 
as 20 meters and then listen for MacMillan. 

THE Turk has decided to modernize him- 
self as far as radio is concerned, and the 
Radio Corporation of America seems likely 
to get a contract to build a huge station at 
Angora. The former station there was of 
German construction and, according to the 
press dispatches, it is not suitable for trans- 
oceanic traffic. It will probably be repaired and 
modernized sufficiently to carry on whatever 
European traffic may originate at this point. 

HPHE Navy has put the airplane and radio 
1 to a new service in which they prove to be 
valuable aids in naval maneuvers. The mod- 
ern gun has such a range that the target may 
be out of sight, or at least so far away as to 
make visual observation extremely unreliable. 
By having an observer equipped with a radio 
telephone in an airplane hovering over the 
target, the fire control officer on board the war- 
ship is at once notified of the accuracy of his 
fire. This method of control, using two-way 



communication, is so rapid and accurate that 
proper corrections can easily be applied to 
successive broadsides without interfering at 
all with the rapidity of fire. 

FROM the radio research laboratory of the 
Soviet Government at Nijni Novgorod 
comes news that the workers there are perfect- 
ing a water-cooled triode.tube. Apparently 
the scientific workers, or their press representa- 
tives, are going along the same independent 
lines of endeavor as are their experimenters in 
the fields of economics and sociology. Could 
they but profit by the experience of others they 
would find that the triode being "developed" 
there had already been developed successfully 
here quite some time ago. 

THE Senate has just authorized the con- 
tinuance for two more years of the private 
use of Pacific Naval Radio stations. The De- 
partment of Commerce recommends this use 
of the Government's stations, for it is their 
opinion that the pri- 
vate stations on the 
west coast are not 
now in a position to 
undertake efficiently 
the transmittal of 
all the commercial 





THE EXPERIMENTAL SHORT WAVE ANTENNA OF KDKA 

At East Pittsburgh. The high wooden poles to which the fan antenna is attached forms the experimental 309 
meter antenna from which regular programs are radiated. The shorter vertical pole above the roof of the 
building is the short wave antenna. The oval at the right shows a close-up of the short wave transmitting 
antenna. Note how short the actual antenna is and that the conductor itself is rigid. Rigidity of the antenna 
conductor is absolutely essential where very short waves are being transmitted. Signals from this short wave 
station have been recently heard in Australia, a distance of about 1 1,000 miles from Pittsburgh 



2O4 



Radio Broadcast 




JOSEPH C. SMYTH E AND ANTHONY GERHARD 
iBoth of New York City who won the awards of the Executive 
Radio Council of the Second Radio District for commercial radio 
code speed proficiency. Mr. Gerhard copied 56^ words a minute 
without an error. It is almost impossible to send the Continental 
code by hand at such a speed and the achievement of such a record 
is remarkable 



112 meter wave and picked up 
by the Radio Corporation's ex- 
perimental laboratory on the 
outskirts of New York. From 
that point the signals went by 
wire to control station wjz. 

So the movement for trans- 
atlantic broadcasting, started by 
RADIO BROADCAST in November, 
1923, has gone on. First by KDKA 
sending its signals to control 2to 
in London and now we have our 
stations controlled by signals 
emanating from London. To be 
sure the reception of the Lon- 
don program here was so poor 
that the encounter must be 
recorded as a victory for Static, 
but it is a beginning and we can 
expect to hear the chimes of Big 
Ben with ever increasing dis- 
tinctness and faithfulness of 
reproduction. 

Transatlantic Telephony 
Is Not Yet 



and private messages which are being sent 
to-day. "Continuation of the service by the 
Navy is necessary," says Senator Jones (Rep., 
Washington), "because the private agencies 
have been unable so far to complete construc- 
tion of facilities and handle all the messages. 

The Progress of International 
Broadcasting 

FREQUENTLY the press tells us that the 
programs of KDKA and other American 
stations have served for operating the 
English stations, thus giving our English 
friends the same programs as we were listening 
to. Never has this been accomplished, how- 
ever, in the reverse direction. It seems more 
difficult for us to receive a European station 
than for them to hear ours. A short time ago, 
however, a start was made which at least shows 
us the difficulties encountered. 

The Radio Corporation station, wjz, has 
on several occasions lately been actuated by 
signals received from 5xx Chelmsford, Eng- 
land. The transatlantic signals were sent 
across the water on a 1600 meter wave to Bel- 
fast, Maine, and from there rebroadcast on a 



N HIS recent annual report, 
H. B. Thayer, Chairman of 
A the Board of Directors of 
the American Telephone and 
Telegraph Company, reviewed his company's 
attitude toward radio development. 

"In view of the great public interest in wire- 
less telephony, it seems proper to mention the 
continued preparation of the British Post 
Office for transmission from Great Britain. 
When that is completed it is expected that the 
experiments referred to in the annual report of 
1922, will be resumed, and that experimental 
conversations with this country will follow. 
It is impossible at present to predict the date 
of telephone conversation with Great Britain 
or even to predict, on the basis of present con- 
ditions, that it will be a practical and commer- 
cial possibility, taking into consideration other 
difficulties. Any other applications of wire- 
less telephony to telephone service, except 
in minor instances where wire connection is 
impossible, appear even more remote." 

When Trains Are Run by Radio 



W: 



HEN an engineer is giving a technical 
talk to laymen not well acquainted 
with the field being analyzed, he is 
very likely to make statements that will appeal 
to the imagination of his listeners. With the 



The March of Radio 



205 



idea of gaining their attention and interest, he 
is likely to venture much farther than he 
would if talking to a number of fellow engin- 
eers. We therefore take with a grain of salt 
a prediction of Mr. G. Y. Allen, of the Radio 
Department of the Westinghouse Company, 
given in a talk before the New York Railroad 
Club. After telling of the possibility of guided 
radio waves, that is, high-frequency current 
over wires, Mr. Allen went on to tell of the 
uses to which such currents could be put in 
railroad operation. "It is entirely feasible," 
said he, "through a combination of electric 
controls, and radio supervisory control, to 
start a train without a crew from a station, 
run it at full speed over clear tracks, and to 
slow down and stop it automatically in accord- 
ance with automatic block signals, giving to a 
central despatcher at the same time complete 
supervisory control of all of the movements of 
trains on a system." 

Certainly all these things are possible, for it 
was only a short time ago that a warship was 
completely controlled in its course by suitable 
relays actuated by means of radio signals. 
But just as our warships still require crews of 
more than a thousand men to handle them, so 
our trains will, for quite some time to come, 
require the crews to which we are accustomed. 
For the time being, we prefer to have a train 
controlled by an experienced engineer rather 
than by a fraction of a watt of high-frequency 
power which, as we all know, may have all of 
its good intentions seriously interfered with, 
and possibly thwarted al- 
together, by static and 
other disturbances. 

More Facts About 
Radio Transmission 



EVER since Marconi's 
first transatlantic ex- 
periment, attempts 
have been made to explain 
the difference between night 
and daylight transmission, 
the effect of wavelength on 
the distance a signal could 
travel, the reason for the 
difference in receiving be- 
tween summer and winter, 
and many other observed 
facts. With the ever in- 
creasing use of short 
waves, we are more than 
ever convinced that much 
of our supposed knowledge 



of how radio waves are propagated is not 
based on fact. Waves 100 meters long should 
theoretically travel but a short distance before 
being dissipated, but in spite of this, they, at 
times, reach half way around the world. 

Two of the engineers of the Bell Telephone 
Laboratories, W. H. Nichols, and J. C. Shell- 
ing, recently published a preliminary note on 
some theoretical work they are carrying out. 
This note states that, due to the combined 
effects of the ionized (electrified) upper atmos- 
phere and the earth's magnetic field, peculiar 
effects on radio wave propagation may be 
expected. The theory, logically based on the 
known behavior of electric charges moving in 
magnetic fields, seems capable of explaining 
the remarkable fading and bending to which 
we well know the average radio wave is sub- 
jected. Possibly even the peculiar effects 
noted during the January, 1925, eclipse would 
prove explicable in the light of this new analy- 
sis. Dr. G. W. Pickard has just presented an 
interesting paper before the Institute of Radio 
Engineers, giving his findings on radio trans- 
mission during the recent sun's eclipse. 

Wireless Vision Achieved 

SUCH an announcement recently ap- 
peared in the London press! Strange 
and unbelievable as this concept of tele- 
vision might have seemed ten years ago, it 
now seems almost sure to materialize at some 
time not far distant. The idea of seeing what 





PACHYDERM AND MICROPHONE 

Station wjz, New York, recently broadcast the sounds and scenes of the 

circus. '"Dolly," a two-year-old elephant, is doing the right thing by the 

radio audience 



2O6 



Radio Broadcast 




GEORGE BERNARD SHAW 
London; Author and Playwright 

" // / could see and hear a play from my fireside, 
I would never enter a theatre again. I shall 
not prophesy, but I remind our managers that 
theatre-going is eery dear, very inconvenient, and 
horribly stuffy and promiscuous. Unless they 
can overcome those disadvantages by the over- 
powering fascination of good plays, good acting, 
and theatres that are like enchanted palaces in- 
stead of hotel smoking rooms, broadcasting will 
knock them out." 



is taking place a thousand miles away would 
have been classed as the working of an un- 
balanced mind a decade or so ago, but now, 
after millions of us have heard, with perfect 
intonation, voices of speakers thousands of 
miles away, why should we be surprised at 
seeing things from the same distance? It is, 
as a matter of fact, as difficult a concept to 
picture radio carrying on voice communica- 
tion- as it would be to have it carry picture 
messages to our eyes. In voice communica- 
tion, sound has to be changed to electro- 
magnetic waves to transmit the suitable 
energy impulses and then these have to be 
changed back to sound for the benefit of the 
listener. The eye requires electromagnetic 
waves for its activation, and this is exactly the 
form of energy used in radio communication. 
The transmission of pictures by radio has 
already been accomplished and many examples 
of these pictures have been printed in the daily 
papers. By most of the present methods it 
takes about twenty minutes to transmit a 



five-by-seven-inch picture. This process is 
really television. If the distant scene remains 
fixed for some minutes, it can evidently be 
sent by radio to the distant onlooker. Instead 
of gazing into the fabled crystal sphere, how- 
ever, he would look at some kind of a chart, 
ink marked or photographic, upon which the 
distant scene would be slowly reproduced. 

Now, if we imagine that such pictures could 
be reproduced in one tenth of a second instead 
of twenty minutes, wireless vision would be 
achieved. Thus the speed must be increased 
some thousands of times over its present 
value, but this is not at all unlikely. Many 
of us have seen the oscillograms by which 
the telephone engineer analyzes his sounds 
and the power engineer discovers what pe- 
culiarities exist in his transmission lines. 
Such pictures of electric current are reasonably 
accurate if the wave to be photographed does 
not reverse more rapidly than about one thou- 
sand times a second. To get pictures of fre- 
quencies higher than this has not seemed 
feasible in the past, yet recently it has been 
found possible to photograph electric cur- 
rents which are reversing as rapidly as twenty 
million times a second. Here is an increase 
of speed of about ten thousand times, accom- 
plished by an ingenious change in the method 
of photography employed. Instead of using 
light waves to affect the photographic plate, 
the electrons themselves, by the activities of 
which ordinary light waves are set up, are 
used to bombard the sensitized gelatine. This 
revolutionary step has increased the speed of 
oscillography thousands of times. By a 
similar application of the electron's activities 
to the problem of radio vision, the solution 
does not seem improbable. 

We Need More Delicacy in Radio 
Advertising 

THE American Telephone and Telegraph 
Company, as has been frequently stated, 
is experimenting with the commercial 
possibilities of broadcasting. Their station, 
WEAF, is admittedly an advertising venture. 
To be sure, much excellent material is sent 
out over this channel which brings the owners 
of the station no financial return, but in the 
course of a week many hundreds of dollars 
find their way into its coffers through the ap- 
pearance of the Gold Dust Twins and other 
organizations of a like character. The price 
of the station for broadcast purposes is high, 
but not so high, we imagine, that the annual 
balance does not have to be written in red 



The March of Radio 



207 



figures. Certainly its income from adver- 
tising is much greater than that of any other 
station. The entire radio field looks to it as a 
trail blazer in the realm of radio broadcasting. 
In the interest, then, of radio advertising, we 
suggest that altogether too much time and too 
many words are spent in telling us who is pay- 
ing for the next hour's operation of the station. 
A mere statement that the Happiness Candy 
Stores are going to give the next hour's enter- 
tainment does not harm the listeners or the 
candy business, but to listen to a stiff, stereo- 
typed eulogy of this special brand of candy is 
irritating, to say the least. Probably the 
candy firm, in common with others "using the 




PROFESSOR MAR1US C. A. LATOUR 
The French radio inventor, whose patent claims 
on many important radio devices and circuits have 
been recognized by the American Telephone & 
Telegraph Company, the Radio Corporation of 
America, and others. The Hazeltine group of 
manufacturers purchased the American license for 
the Latour patents and the A. T. &. T. Company, 
and the Radio Corporation have non-exclusive li- 
licenses from Prof. Latour whose patents are such 
as to involve, so he claims, every radio receiver made 

facilities" of this station, specifies how much 
propaganda must be poured into their radio 
channel. If this be so, we suggest that a bit 
more music and a correspondingly decreased 
period of self-approbation would be more con- 
ductive to candy buying. It takes but little 
propaganda to give to radio advertising a dis- 
tinctly negative value and that negative value 
has been reached several times by the clients 
of WEAF. 

Electrical Exports Are Increasing 

THE Department of Commerce reports 
that during 1924, the total of our electri- 
cal exports approximates $85,000,000, 
a $12,000,000 increase over 1923. Most of 
this money is spent for machinery and trans- 
mission line equipment, but radio and its ac- 



cessories are showing an ever-increasing share 
of the export business. The total for radio is 
estimated by the department to be $5,000,000. 
Dry batteries alone show an export value of 
nearly $800,000 during the past year. 

South America, which last year was one of 
our principal foreign customers, has dropped 
from third to fourth place, probably due to the 
activity of German merchants, especially in 
such countries as Argentina where German 
sympathizers are very active. 

Although the total of our electrical ex- 
ports shows a very considerable figure, this 
pales into insignificance when our own ex- 
penditure for engineering projects is con- 
sidered. Electrical power plants, dams, water 
and sewage systems, for 1924 mounted to the 
enormous total of $2,002,533,000. It's no 
wonder our engineering schools find great 
demand for their graduates when such techni- 
cal activity prevails throughout the country. 



Interesting Things Interestingly 
Said 



F\AVID SARNOFF (New York; vice president 
*-* and general manager of the Radio Corporation 
of America): "In whatever direction radib may 
develop, it will be, I believe, toward supplementa- 
tion, not substitution. The truth is, printer's ink 
achieves something that radio cannot achieve; 
conversely, the security of radio lies in the fact that 
it provides a different service than the printed word 
ever rendered or ever could render." 

LJUGH S. POCOCK (London; Editor of the 
Wireless florid): "To-day a number of broad- 
casting stations in different parts of the world are 
making use of Esperanto as a means of linking up 
with other countries. 

". . . The employment of short waves for 
long-distance transmission using low power, the im- 
portance of which was first demonstrated by the 
amateur worker, has provided those who conduct 
experimental work with a means of linking up with 
their fellow workers all over the world, however dis- 
tant. Demonstration has, in fact, already been 
given that there is no point on the globe so remote 
that it cannot be reached on short waves by ama- 
teurs, even when using very limited power. As the 
range over which amateurs communicate has been 
gradually extended, so the necessity for some com- 
mon language has arisen. 

". . . To-day it is not by any means an un- 
usual occurrence when overhearing short-wave inter- 
communication to come upon the exchange of com- 
ment in Esperanto between amateurs of two differ- 



208 



Radio Broadcast 



ent countries whilst experimental work is being 
carried out, each understanding the other without 
difficulty, although their native languages may be 
entirely unintelligible to either." 

CRANK T. ST ANTON (New York; president 
Frank T. Stanton and Company): "I am not 
at all in sympathy with statements I have heard 
that the radio industry has been overfmanced. In 
fact, I still maintain that the radio industry is under- 
financed. There is hardly a question that if the 
tremendous sums that have been paid for radio se- 
curities during the past six months had all found 
their way into the treasuries of the companies 
rather than into the pockets of the original organ- 
izers, a vastly different story could now be written 
regarding the market for securities representing 
manufacturing enterprises." 

CRANK J. McENIRY (Denver, Colorado; 
General Electric Company, station KOA): 
"Never did Marconi, Armstrong, Hazeltine, Alex- 
anderson and other famous experimenters dream 
that some day, the results of their efforts radio 
would be employed to capture murderers and ban- 
dits, put across community chest drives, detect 
human ills, recover lost dogs, and bring together 
parents and wandering or kidnapped' children. 
What radio will accomplish and what is predicted 
for it are two entirely different things, according 
to experts in this field. On the face of it, however, 
radio is confronted with the peculiar problem of 
living up to everything that is expected of it." 

(~*. C. FOSTER (New York; President of the 
^^ American Piano Company): "The question as 
to the effect of radio on the piano business is fre- 
quently asked. We believe that radio is decidedly 
helpful. It is increasing the knowledge and appre- 
ciation of music, and it is awakening an interest in 
many to whom it has hitherto been a matter of in- 
difference. It is increasing the desire to hear better 
music, especially in the home. The enjoyment that 
the radio brings has unquestionably pointed a way 
to even greater enjoyment through the actual pos- 
session of a means of making music, which leads 
directly to the thought of a piano." 

r\R. E. F. W. ALEX ANDERSON (New York; 
*-* Chief Consulting Engineer, Radio Corpora- 
tion of America): "The shortest element of the 
telegraphic signal is the dot. The higher the sig- 
naling speed the shorter is the dot. Thus, while 
the wave amplitude is kept constant the total 
energy contained in the dot sign is inversely propor- 
tional to the speed of signaling. When the strong- 
est single atmospheric impulse prevalent at any 
time contains as much energy as the dot in the 
telegraphic code it may be mistaken for a dot, or 
it may break up a dash into two dots, thus causing 
false telegraphic signals. It is therefore necessary 
to maintain a speed of signaling in which the total 
energy of the dot is somewhat greater than the 
maximum energy of a single atmospheric impulse. 
Thus, if a wave amplitude is doubled, the length 
of the dot may be shortened to one-half. This ex- 




Underwood & Underwood 
G. Y. ALLEN 

New York; Radio Department, Westinghouse 

Electric & Manufacturing. Company 

" Tbroitgb the use of modern developments in 
radio, it is entirely possible to operate electric 
trains from a central control office. I do not 
wish to be understood as advocating the elimina- 
tion of the molorman, conductor, and crew. No 
mechanical device, however perfect, can take tbe 
place of human intelligence, but it is interesting 
to note some of tbe possibilities of radio control. 

"It is now entirely feasible, through a combina- 
tion of automatic control and radio supervisory 
control, to start a train without a crew from a 
station, rim it at full speed over clear tracks, slow 
it down or stop it, in accordance with the signals 
of an automatic block signaling system, start it 
up again when the signals clear, stop it at its 
next station stop, and open its doors." 



plains why in practice the telegraphic amplitude is 
double the length of the wave amplitude and also 
why it is inversely proportional to the atmospheric 
disturbance." 

A LBERT E. HAASE: (New York; in an article 
** in Printers' Ink): "There is no doubt in the 
minds of many who are getting their livelihood from 
radio that if this mad rush to get the advertisers' 
dollar for the support of radio continues, radio itself 
will suffer. And that would mean public resent- 
ment against advertising all forms of advertising, 
for the public does not distinguish between adver- 
tising mediums. It is this point that makes it 
imperative for all thoughtful manufacturers to 
watch and study the attempts that are being made 
to turn radio broadcasting into an advertising 
medium." 




THE s. s. "ARCTURUS" 

The marine headquarters of William Beebe, the scientist and explorer. The Arcturus is the most 
perfectly equipped ship for scientific exploration in existence. A 3! kilowatt continuous wave 
radio transmitter aboard keeps the expedition in constant touch with the mainland. Exclusive news 
dispatches from Doctor Beebe appear in the New York Times, telling of the findings of the party 



Radio's Part in the Sargasso Sea 

Exploration 

Dr. William Beebe's Scientific Expedition to the Unfamiliar Reaches of 
the Atlantic Ocean is Constantly in Touch with the World by Radio 



BY ALFRED M. CADDELL 



WHAT did you write on that 
paper that you put in a bottle 
and cast from the ship on your 
last sea voyage? Have you 
heard from some romantic young lady, or from 
some ne'er-do-well beachcomber who has 
found your bottled message buried in the 
sands of some distant resort? If not, then the 
possibilities are that your bottle has followed 
;in the wake of a derelict on its way to the 
Sargasso Sea. Situated between two legend- 
ary points on the compass, somewhere between 
Africa and the Continent on the west, lies the 
Sargasso Sea that mysterious part of the At- 
lantic Ocean which, it is thought, marks the 



grave of the fabled continent Atlantis, and 
which has now become the graveyard of dere- 
licts floating wreckage of all sorts. 

Curiously enough, human nature likes to 
build fables and yarns upon which to feed the 
imagination, and there are many weird stories 
told of this great waste of seaweed and drift- 
wood. And out of these stories there has 
grown the belief that, perhaps, after all, there 
may be a Sargasso Sea. Once that is admitted 
it is logical to conclude that there is a sunken 
continent under that grayish expanse of slug- 
gish water and that on the continent, if explor- 
ation were possible, there might be found 
treasures in gold and ornaments and in his- 



210 



Radio Broadcast 



torical value, equal to those uncovered when 
Tut-ankh-Amen's tomb was first opened. 

And so, not so much in the hope of discover- 
ing lost treasure, but rather in the hope of 
obtaining valuable research data, an expedi- 
tion has started for the Sargasso Sea. The ex- 
pedition under the direction of Dr. William 
Beebe, has been fortunate in obtaining a party 
of noted scientists, among whom is Dr. William 
K. Gregory of Columbia University and the 
American Museum of Natural History. 



The Ardurus, for so the vessel that has been 
chosen for this important work has been 
named, is the largest ship that has ever been 
employed in explorations of this character. 
She is 280 feet long and has a 46-foot beam. 
She is equipped with every facility required to 
probe into the mysterious Sargasso's secrets. 
Her laboratory, which is undoubtedly the fin- 
est afloat, is provided with every scientific 
instrument which can possibly be of service in 
making observations of whatever forms of life 
the dredge of the ship may bring to the surface. 
The Ardurus is equipped with a drum on 
which is wound seven miles of cable, so that the 
ocean may be dredged at any known depth. 
The cable is lowered with trawls which auto- 
matically close at prescribed depths, so that if 
any deep sea monsters become enmeshed in 
the trawls, the depth at which they live will 
be known. This will assist the scientists 
in tracing, step by step, the evolution from 
surface fish forms to the extraordinary 




PLUMBING THE MARINE DEPTHS 

From the bow of the Ardurus. A specially arranged bridge from the bow of the ship has been rigged so 
that the members of the party can work directly over the sea instead of having to drop a line over the side. 

The insert shows Doctor Beebe 



Radio's Part in the Sargasso Sea Exploration 



211 



marine life which inhabits the lower regions 
of the sea. 

THE SEARCH FOR UNDERWATER TREASURES 

DEEP sea monsters provide treasure for 
almost inexhaustible thought. Many 
fish with remarkable lighting systems have 
been caught. Some of them are said to be 
aflame with light, so that they look more like 
a Hudson river night boat than fish, while 
others carry green, red, yellow, and pink 
lights. Some have peculiar shaped lanterns 
at the ends of long feelers, while the bodies of 
others of this peculiar species of fish are 
studded with blazing search lights. Some 
have eyes from which radiance streams, and 
others are continuously lighted. It is believed 
that only a small portion of the various species 
of lighted fish have been caught, so that they 
will be subjected to very careful study on this 
expedition. 

Another interesting phase of deep-sea life 
will also engage the attention of the scientists. 
Deep sea fish, it 
is known, fill 
their tissues with 
compressed gases 
to resist the pres- 
sure of the water 
at great depths, 
so that when 
they are hoisted 
to the surface, 
the diminishing 
pressure no 
longer neutra- 
lizes the pressure 
of gas from with- 
in, causing them, 
sometimes, to ex- 
pand or burst 
like popcorn. 
Other fish are 
able to live at 
various levels by 
means of mus- 
c u 1 a r valves 
which release the 
compressed gases 
from their tissues 
as they rise, and 
replenish their 
chambers again 
when they de- 
scend. Needless 
to say, special 
study will be 
given to the com- 



pressor and decompressor systems possessed 
by these monsters. 

Then on the Ardurus there are many tanks 
and one great aquarium in which many 
things of interest will be brought back to New 
York when the explorers return from that re- 
gion of the South Atlantic where the Sargasso 
is supposed to be. 

But best of all, one of mankind's recently 
developed wonders is playing an import- 
ant part in this expedition. We will let 
Charles J. Pannill, General Manager of the 
Independent Wireless Telegraph Company, 
tell us about the radio installation on board 
the Ardurus. 

" If you are able to tune-in on a 2400 meter 
wavelength," said Mr. Pannill, "y u will be 
able to listen-in on some mighty interesting 
press despatches, if you can read code. Here- 
tofore, expeditions have seldom been heard 
from until they returned to their point of de- 
parture, so that when to-day we are able to 
follow explorers, step by step, through their 




THE RADIO CABIN OF THE "ARCTURUS" 

The radio equipment is controlled by the Independent Wireless Telegraph Com- 
pany. The ^returns is a wooden ship built by the Shipping Board during the war for 
the Alaskan trade. It was owned by the Union Sulphur Company and was donated by 
Henry D. Whiton to the New York Zoological Society for this voyage of exploration 



212 



Radio Broadcast 



tribulations and hardships, it only goes to 
show to what extent radio has become a daily 
adjunct in our lives. And, too, it is interest- 
ing to note that the progressive newspaper 
realizes the value of radio from the point of 
view of press despatches. The following ex- 
cerpt from an article in the New York Times, 
takes the reader right to the spot and almost 
enables him to participate in the exploration: 

"We are now at the site of the fabled At- 
lantis on Atlantic Ridge, midway between 
America and Africa, with 2300 fathoms of sea 
below us, and this morning our radio receiving 
set brought to us the lively music of a Pitts- 
burgh orchestra playing 'Hands Across the 
Sea' Souza's march. 

' ' Even with continued heavy seas we have 
brought our heavy dredging apparatus into 
play, and yesterday our first bottom dredge 
brought up glass sponges and volcanic rock 
from a sea abyss three and one-half miles 
below us. 

"The Arciurus has on board a radio instal- 
lation furnished by the Independent Wireless 
Telegraph Company, and consisting of a 
3^ kw. arc transmitter with daylight range 
of approximately 1 500 miles, and also a one- 
half kw. spark transmitter for emergency 
short range work. Doctor Beebe has arranged 
with the New York Times to report an account 
of their operations, which dispatches are han- 
dled through the East Moriches, Long Island, 
station. Thus the public and the philanthrop- 
ists who contributed toward this expedition 
are enabled to read the despatches the day 
after they are sent. What an advance over 
the communication systems of other expedi- 
tions and other days!" 

The Ardurus left the Sargasso Sea some- 
time during the last week in March, and on the 
29th of March, Captain J. S. Howes reported 
by wireless that all was well with the Ardurus 
and her crew, and gave her position as 200 
miles south of Balboa, Panama, in the Pacific 
Ocean. The Ardurus had left Balboa, Canal 
Zone, on the 28th of March and had headed 
directly for the Galapagos Islands, where Doc- 
tor Beebe and his party of scientists intended 
to continue their researches, and also, it is be- 
lieved, to study the Humboldt Current, of 
which little is known. But there was a 
period of two weeks after the Ardurus sailed 
for the Galapagos, where nothing was heard 
from her nothing further at least, than the 
Captain's report on the 29th of March. It 



was then that grave fears for her safety be- 
gan to be expressed, and there was much ex- 
cited comment as to her fate. 

The waters of the Pacific Ocean in the 
vicinity of the Galapagos, and following the 
waters of the Humboldt Current along the 
Peruvian coast, are far from truculent. In 
fact, so calm is it in this immediate vicinity 
that it has become noted for this alone. 

Recently, Dr. Robert Cushman Murphy, 
Assistant Director of the American Museum of 
Natural History, returning from a study of the 
vicinity, with new data on unfamiliar cur- 
rents, told of the unprecedented weather in the 
vicinity of the Humboldt Current, and he ex- 
pressed the opinion that some trouble might 
have been experienced with the wireless outfit 
on board the Arciurus. But there was little 
ground for this belief, for as previously stated 
in this article, the Ardurus is fully equipped 
and ready for any possible emergency to her 
radio or to any other part of her scientific 
equipment. 

Members of the New York Zoological 
Society were unable to explain the Ardurus' s 
silence, for the vessel had previously com- 
municated directly with East Moriches, Long 
Island, sending her position to the radio station 
there every day. President Henry Fairfield 
Osborn of the Museum of Natural History, 
sailed from Miami on the steamship George 
Washington recently. The George Washing- 
ton has the same equipment as that in- 
stalled on the Ardurus, but though the 
operator on this vessel attempted persist- 
ently to get into communication with the 
expedition, he was unsuccessful. Then it was 
that all vessels south of the canal zone were 
asked to call the Ardurus, and the Naval radio 
station at Darien, Canal Zone, was instructed 
to send out her call. 

What then, had happened to the Ardurus? 
Had her officers and men found another 
Sargasso Sea, never to return and tell us about 
it? Or, was it merely that old complaint 
"static" about which we hear so much now-a- 
days? Perhaps, even then, they were ap- 
proaching the land of the tortoise, the 
Galapagos, the mysterious and romantic Gala- 
pagos of the i6th century Spanish buccaneers. 
And, indeed, this proved to be so, for on April 
i ith, it was learned through the Navy Depart- 
ment, that once again the Ardurus had been 
heard from and that all was well with those on 
board. 



'CHe Listeners' Point of" 

6y eJ^ennie Irene 



Has Radio Any Relation to tke Supernatural? 



IT WAS in 1906 that Dr. Thomas Troward 
put forth the statement in his Edinburgh 
Lectures on Mental Science that there is 
no such thing as time or space: that, as 
the smallest portion of the ether contains all 
the elements of the whole, then every portion 
of the whole is within this smallest portion. 
Therefore, the entire universe is in one place 
and every place at one 
and the same time. 
Thus, neither time 
nor space exists. 

This was, of course, 
long before the days 
of broadcasting, and 
the lectures aroused, 
except among those 
who had themselves 
gone deeply into the 
subject, the ridicule 
with which all new 
ideas are received. 
People thinking only 
on the surface in- 
terpreted Doctor 
Troward as saying 
that you did not have 
to cover any ground 
whatever to get from 
New York to China 
because there wasn't 
any ground. And so 
they went on. 

The simple fact was that Doctor Troward 
was anticipating radio. Had you asked him, 
"What is the difference in time between 
London and New York?" he would have re- 
plied, "There is no difference, nor between 
any other two points in the world, no matter 
how far they are separated according to the 
estimate of the geographers." 

We know now that this is true, and has been 




VLADIMIR RASSOUCHINE 

Pianist, who was heard recently at KGO 

and gained favor with a large number of 

listeners 



true since ever the earth was formed. The 
fact that while it may be daylight in this coun- 
try it is night in China has nothing to do with 
the matter as set forth by Doctor Troward. 
He deals with those elements outside of the 
material that control our lives, and over 
which we have practically no control, and, 
therefore, foolishly grope our way blindly 
among all the other 
blind. 

Years ago for it 
must have been quite 
a time before these 
Troward lectures were 
brought before the 
public, F. Marion 
Crawford wrote a 
novel called Mr. 
Isaacs, in which the 
scenes are largely laid 
in India, and the 
psychic powers of the 
Hindoos, figure in the 
story. One of the 
characters remarks 
quite casually to 
another that he saw a 
mutual friend of theirs 
in a town some one 
hundred miles distant 
from his home al- 
though he knew 
perfectly well that 
the friend was in his home. 

Marion Crawford states that long after 
this book was published, a woman asked him: 
"Why did you put such an absurd incident 
into a novel that, in the main, is plausible?" 
Mr. Crawford replied that while he was in 
India he heard many such statements, and 
others that seemed even more impossible of 
belief. He asked the man who had seen his 



214 



Radio Broadcast 




THE EVEREAD^ 



Whose artistic playing is frequently heard during the programs of the Eveready Hour, broadcast each 
Tuesday from nine to ten. From left to right they are, Alex Hackel, violinist, Edward Berge, pianist, 

Jacque de Pool, 'cellist 



friend one hundred miles distant from where 
he was in the body, just what he meant. The 
Hindoo said, "But that is not unusual. By 
controlling vibrations one can project his per- 
sonality through the ether to distant points." 

Radio is projecting personalities in the form 
of photographs to distant points, by a man- 
made machine. Perhaps the Hindoo was 
right and one's personality can be projected 
by a God-made machine, the mind. 

Impossible? Who can say that anything 
is impossible? 

According to Edward Jewett of Detroit, who 
talked in an interview on what the boys have 
done for radio, they do not know the word 
"Impossible." He said: 

"The boy mind grasps the theory of radio 
better than can the man mind because to the 
boy mind there are no inhibitions and im- 
possibilities. Men, as they become men, learn 
that so many things, 'cannot be done.' The 
boy doesn't know that. So he goes ahead 
and does it. ... I asked one youngster 
what he did when he discovered that a thing 
could not be done. 'Find out how to do it,' 
was his prompt reply." 

(Perhaps by using this boy's method we may 



learn how to control vibrations with the mind so 
that we may be benefited by such control!) 

To revert to Mr. Jewett: 

"The youth grasps at the intangible far 
better than the grown person. He can see 
a thing that isn't there, and the minute that 
he sees it, then it is there. His imagination is 
neither tired nor spoiled. Boys think and say 
uncanny things. One remarked to me once, 
' It's curious to know that every voice in all the 
world is here, now, in this very room, isn't it?' 

"You mean," I countered with the old 
man wisdom we are so likely to effect, "that 
it's here if we bring it here." 

"'No,' said he, 'it's here now if we will 
give it a fair chance to reproduce itself. 
If we don't hear it, that's our fault." 

And yet you may be sure that youth had 
not read Troward although he was stating 
the basic principle of his Edinburgh lectures. 

How Archaeology "Came Over" on 
the Radio 

IF YOU missed hearing Joseph Emerson 
Smith give a talk last month through sta- 
tion KOA, Denver, then you are unfortunate. 



The Listeners' Point of View 



215 



Mr. Smith was a member of the expedition 
sent by the Colorado State Museum to the 
recently discovered prehistoric city of pit- 
houses extending along the tops of a straggling 
series of mesas in southwestern Colorado, and 
that swing from a point near the Colorado- 
Utah border in the Paradox Valley to Pagosa 
Springs, Colorado, and then south, well into 
New Mexico. 

This is the largest lost city yet discovered 
on the American continent. Its civilization 



goes back to a period previous to that hitherto 
believed to be the oldest that ever existed on 
this continent, antedating the cliff dwellers 
by at least one thousand years. It is com- 
posed of scores of separate and distinct units, 
which, for the sake of defense advantages, 
were confined to the tops of mesas or table- 
lands, high above the valleys. Five hundred 
pithouses in one group alone have just been 
mapped in what is known as Chimney Rock. 
There are tens of thousands of these pit- 




AN ANCIENT WATCH TOWER 

And skeleton of a prehistoric woman which were uncovered in the nearby pithouse, inhabited twenty-two 

centuries ago in what is now Colorado. A lecture on these archaeological discoveries was given at station 

KOA, Denver, and is commented upon elsewhere in this department 



2l6 



Radio Broadcast 



houses, large and small, dotting the tops of 
the mesas. Archaelogical surveys indicate 
that they were excavated by the original 
builders to a depth of from three to five feet, 
and were surrounded by sleeping chambers 
and granaries. Entrance to these homes was 
through a steep decline or tunnel, accommo- 
dating only one body at a time. Fires were 
apparently built in the exact center of the 
large or main room, and an opening at the 
roof was skillfully fashioned to let out the 
smoke. 

So far as investigation has at present gone 
it has been discovered that these people had 
a crude knowledge of astronomy, and carried 
on truck gardening and irrigation. Their prin- 
cipal crops were gourds, tubers, corn, melons, 
yucca and greens. Figurines have been dis- 
covered, of rare design and finish, and pot- 
tery that might well be used for decorative 
purposes to-day. 




LUKE HILL 

No, the small boy, who is all of seven, isn't impersonating Oliver Twist and asking 
for "more." As a singer he was the "hit" of the radio show given recently for 
the benefit of "The City of Childhood," maintained by the Loyal Order of Moose 
for the dependent children of their deceased brothers. It was presented through 

WJJD 



The photograph reproduced on page 215 
shows the remains of an old watch tower, 
and also the perfectly preserved skeleton of 
a woman about 35 or 40 years of age, who 
was about five feet ten inches in height. It 
will be seen that the right cheek was resting 
on the right hand, and the left arm was placed 
across the breast. The knees were flexed. Be- 
side the skeleton was an unusual elaborate gray 
bowl decorated with a conventionalized de- 
sign of butterflies. Near by was a complete 
pottery face, that of a doll which originally 
was supported by a corncob. 

Mr. Smith has been quoted indirectly, be- 
cause to attempt quoting him verbatim would 
be an injustice to the exceptional interest with 
which every moment of this talk was filled. 
Station KOA has put on many fine features 
during its short existence, but probably 
nothing of greater interest to a certain 
class of listeners-in than this one. 



American Mu- 
sic Is Inferior 
to None 

IN THE course 
of a very inter- 
esting article 
comparing British 
and American radio 
receivers, the au- 
thor says, in the 
Wireless World and 
Radio Review (Lon- 
don): "It may be 
said definitely that, 
taken as a whole, 
British wireless sets 
and components 
are superior to 
those manufac- 
tured in the United 
St ates, both in 
quality of work- 
manship, and in 
quality of repro- 
duction. This is 
not so much due to 
the fact that Amer- 
ican manufacturers 
are lacking in skill 
in the design of 
good transformers, 
etc., as it is due to 
the mentality of the 
American people. 
Anybody who is 



The Listeners' Point of View 



217 



intimately ac- 
quainted with 
modern American 
music, or has had 
the opportunity of 
comparing the per- 
formances of the 
average quality 
orchestras in thea- 
tres and restau- 
rants in the two 
countries, will 
readily understand 
why the quality of 
reproduction in the 
British sets is so 
greatly superior to 
that in those which 
emanate from the 
U. S. A. Indeed, 
the performance of 
an orchestra which 
would be consid- 
ered mediocre in 
England, is usually 
termed, ' High- 
brow 'on the other 
side of the water." 

Taking restau- 
rant music by and 
large in England, 
this is no doubt 
true. Also, all who 
have taken the 

trouble to inform themselves regarding radio 
programs in that country as compared with 
American programs, know that England gives, 
on the average, music far superior to ours. 

But the writer of this article, M. P. Vincer- 
Minter seems unconsciously, to carry the 
impression that all music produced in Eng- 
land, whether by radio or through the usual 
public channels, is superior to American mu- 
sic. In truth, the opposite is exactly the case. 
Except for her great choruses which give 
yearly festivals, English music as heard in 
concert halls and opera houses cannot for 
a moment stand comparison with the great 
attractions in these same lines available in 
this country every season. England has been 
called, "The Ballad Country," for the reason 
that her people have never risen, as have the 
American people, to a point of appreciation of 
the lovely and masterly songs of such com- 
posers as Schubert, Schumann, and Brahms. 

Also, where this country has well nigh a 
dozen orchestras of the highest rank, England 
has one and that is the London Phil' ar loric. 




THE CAMERON SISTERS 

Fair charmers with the flute and harp who 
broadcast an attractive program from KGO 



Covent Garden Opera has been discontinued 
since the war, while here the Metropolitan 
and Chicago forces are still carrying on. All 
these points are cited, not to correct the writer 
in the Wireless World, but because to some 
he may unconsciously give the impression that 
he is talking about American music in general. 



When an Announcer Confides 



M 



R. H. W. ARLIN, of station KDKA, 
who made his debut as one of the 
world's pioneer radio announcers in 
1921, assures the public that, "Although I 
have been continually on the job ever since 
then, it has never grown stale. This, for the 
reason that there are always certain indi- 
viduals who furnish diversion. Such as, for 
instance, the woman who telephones: 'I have 
just left a package of pajamas on the street 
car, and would like to have the service of 
your station in recovering them.'" 

"Or, 'I have just arrived at the Pennsyl- 
vania station and have some relatives living 



218 



Radio Broadcast 



in the city, but do not know where they live. 
Will you please announce over the radio that 
I am here and waiting for them to get in 
touch with me?" 

Or, when Christine Miller Clemson, for 
many years one of the leading concert con- 
traltos of the country, was requested to sing, 
"Red Hot Mama!" 

What the Flonzaley Quartet Think of 
Radio 

A)OLPH BETT1, first violin and di- 
rector of the Flonzaley Quartet, in 
speaking to the present writer of the 
first broadcasting experience of this organiza- 
tion when they were heard on a Victor program 
through WEAF, said: 

"It is incredible, radio. It is the greatest 
influence in the world to-day! It will trans- 
form, perhaps, musical conditions and the 
transition stages may make confusion. But 
it will lead to glorious results. It is still 



impossible for me to realize that we were 
really heard by outside listeners as we played 
in that studio. We sat there, and played with 
the same ease and comfort as if in the parlor 
of friends. When the telephone calls began 
to come in telling how clearly we were heard 
even at a great distance, I could only exclaim: 
'But did they really hear us?' I still cannot 
comprehend. I only know it is marvellous 
and that I am deeply interested.'" 

This from one of the very greatest of living 
musicians. 

The Battleground of Jazz Opinion 

DR. R. S. M1NERD raised quite a 
breeze among the proponents of jazz 
through his letter published against 
cheap jazz last month, judging from the 
letters received by the conductor of this 
department calling him down. He raised 
quite a breeze among the anti-jazzites, too. 
All the letters that have ever been received 




"DO A GOOD TURN DAILY 

Picked members from a number of crack Scout Troops assembled around a radio set to receive instructions 
in hooking up and operating the one-dial Mohawk set which is to be distributed through the Chicago 
Tribune to the blind of that city. The boys are installing the sets and instructing the sightless owners how 

to use them 



The Listeners' Point of View 



219 



by the editor of this department upholding 
jazz, condemn what they call "the classics" 
being devoid of melody. Yet at least ninety 
per cent, of jazz is written from melodies 
drawn from the great composers, distorted 
for jazz purposes. 

Probably, "Yes, We Have no Bananas," is 
not jazz, but the song is taken literally from 
the "Hallelujah" chorus of Handel's "Mes- 
siah." 

IT IS little short of wonderful the way station 
KGO, operated by the General Electric 
Company, keeps up the high standard of its 
programs. Congratulations are well in order, 
not only for this station but KOA at Denver, 
operated by the same company. Both of 
them have fortunately managed to avoid many 
of the pitfalls into which new stations stumble 
through ignorance. 

The Stage and Radio Are Not Op- 
posed 

COSMO HAMILTON, the playwright, 
is among those who are pessimistic 
regarding the effect of radio on the 
theatre. People simply will not go to plays. 
They will stay at home and listen to them by 
radio. 

Can any one imagine an intelligent person 
preferring to listen-in this way to Bernard 
Shaw's "Saint Joan" rather than to attend 
the performance in person? We may be sure 
that the theatre will not be seriously affected 
by radio until sight and sound are absolutely 
synchronized and equally successful in pro- 
duction. And we doubt if even then the pub- 
lic will accept this sort of production as a 
substitute for the real thing. 

WE ARE, indeed, making progress in 
radio music but only because a few (very 
few) stations have progressive program direc- 
tors. In featuring a series of concerts and 
lectures given during February and March at 
the Detroit Athletic Club, station wwj of that 
city made it possible for their listeners to 
hear, in the musical line, William Backaus, 
pianist of international fame, Reinald Werren- 
rath, and Margaret Matzenauer. One could 
not ask for more than this. 

A NY day or evening you can tune-in and 
* hear from one station or another some 
of the latest books discussed. It may in- 
terest the broadcast directors to know that 
many people enjoy this feature who are not 




FLORENCE STERN 

The youthful violinist who has 
been heard through station WEAF 



among those inclined to write letters express- 
ing their commendation. 

THE young woman who, each evening at 
7.05, from station WBZ, Springfield, talks 
to the kiddies is one of the star radio enter- 
tainers along this line. She gives the children 
such worthwhile stories that they are also 
enjoyed by grown-ups, which is the test that 
all stories for children must meet before they 
can be called literature. 

MISTAKES in program printing are not 
infrequent. A short time ago a pro- 
gram contained the announcement, "Valet 
Music from Rosamund Suite by Schubert." 

THERE must be good piano teachers in 
Iowa and Nebraska judging from some 
of the pupils heard through the radio stations 
in those states. 

ALL communications addressed to this de- 
partment should be signed with the full 
name and the address of the writer. Letters 
are sometimes received that contain valuable 
comments or suggestions, but signed with a 
fictitious name. It is contrary to the policy of 
this department either to quote from or other- 
wise to acknowledge any anonymous com- 
munication. 



How to Make a Chemical Plate 

Supply Unit 

A Double- Wave Rectifier Without Any of the Faults of the Usual Type It Is 
Very Simple and Inexpensive to Make and the Parts Can Easily Be Secured 



BY JAMES MILLEN 



THIS article of Mr. Millen's is a careful presentation of a new suggestion for a chem- 
ical rectifier to furnish plate potential. The average person is inclined to think that 
a chemical rectifier is necessarily sloppy and unreliable. This is not precisely true. A 
well-made chemical rectifier is, all things taken into consideration, highly satisfactory for 
use as a plate supply. This unit will furnish plate potential up to 120 volts and current 
enough for any receiver. On tests made on one of these units connected to a receiver in 
our laboratory it was noted that no hum at all was present in the loud speaker or telephones. 
It will be seen that the whole unit can be put together for less than $20, and for those who 
are anxious to build a plate supply unit, we can recommend this highly. Service tests of 
several hundred hours' duration made simultaneously with three complete units failed to 
show any noticeable sign of deterioration in any of the units. The Bureau of Standards 
Technologic paper No. 265, "Theory and Performance of Rectifiers" by H. D. Holler 
and J. P. Schrodt may be found very interesting to those readers who wish to go deeper 
into the theoretical side of this subject than Mr. Millen has. THE EDITOR 



THERE have been many articles pub- 
lished on B eliminators employing 
thermionic tubes, mean free path gas 
tubes, and even miniature dynamotors 
and motor generators. Very little has as 
yet appeared about a system which is in 
many ways superior to any of the others. No 
doubt this evasion of the chemical rectifier is 
due to a considerable extent to the existing 
opinion in the minds of many that this type 
of rectifier is sloppy, inefficient, and requires 
considerable attention. This, unfortunately, 
is true of the majority of borax rectifiers used 
in many amateur transmitting stations. Sev- 
eral years ago when chemical rectifiers were 
first used for that purpose someone suggested 
a solution of borax as an electrolyte and as a 



result borax has been almost exclusively used 
for this purpose ever since. Of all the differ- 
ent solutions available, borax is in my opinion 
by far the poorest. I n fact one is almost justi- 
fied in condemning the chemical rectifier if his 
experience has been restricted to the use of 
borax as an electrolyte. 

Fortunately, however, there are several ex- 
ceedingly fine solutions for use in lead-alumi- 
num rectifiers, and a properly made cell, such 
as is described in this paper, is compact, clean, 
inexpensive,, and efficient. Furthermore, it 
will seldom require any attention. The relia- 
bility of the chemical rectifier when properly 
made is most strongly emphasized by its use 
by one of the largest public utility corporations 
in the world. 




TRANSFORMER 










+ 90 


RADIO \ 
SET 




RECTIFIER 




FILTER 


+ 22 


B 
















u* 



110 V. 
A.C. _ 

FIG. I 

From lamp socket to radio receiver. The illustration shows the entire system as used to change the 
1 10 volt alternating current to a variable d. c. voltage for supplying plate potential to any radio set 



How to Make a Chemical Plate Supply Unit 



221 



Primary 




Pilot Lamp 
Secondary 



High Voltage 
Secondary 



FIG. 3 

A sketch of the transformer which steps up the 
voltage to compensate for the drop in voltage 
through the rectifier. This transformer is easily 
reconstructed from a toy transformer. An addi- 
tional winding of a few turns provides for the pilot 
light current supply 



As the chemical rectifier unit is very much 
cheaper than a tube rectifier, it is possible, 
without greatly increasing the cost of the com- 
plete B supply unit, to rectify both halves of 
the alternating current cycle. This complete 
rectification makes possible the use of a much 
smaller filter system. Still another reason for 
the much greater ease with which the output 
of a chemical rectifier may be filtered is the 
high inherent electrostatic capacity of the 
unit. The capacity of the single unit des- 
scribed in this paper is approximately i mfd. 
as compared with the negligible capacity of 
thermionic tubes. 

Each cell (when used with the solution men- 
tioned below) will stand well over 100 volts, 
which makes it possible to obtain between 80 
and 1 20 volts at the set, depending upon the 
transformer voltage. This is ample when used 
with the average broadcast receiver. Where 
it is necessary to rectify higher voltages, then 
several cells must be used in series. 

CONNECTIONS OF CHEMICAL RECTIFIERS 

THERE are two methods of connecting 
chemical rectifiers. In the first or bridge 
method, Fig. 4, four small cells are required. 
In the second method, Fig. 8, only one cell 



(slightly larger) is required, but a double 
transformer secondary is needed to feed it. 
Thus the saving in rectifier cells in the one case 
is more than offset by the additional trans- 
former secondary required in the other. 

The jar is a three ounce "salt mouth" 
bottle fitted with a rubber stopper having 
three holes, as shown in Fig. 2. The elec- 
trodes are T V mcn rods. The aluminum rods 
must be chemically pure. Commercial alum- 
inum will positively prove unsatisfactory. 
Lead rods, chemically pure aluminum rods, 
and "salt mouth" bottles are carried by the 
large chemical supply houses. Eimer and 
Amend, i8th St. and 2nd Ave., New York 
City can furnish these supplies. In drilling, 
tapping, and cutting the aluminum, extreme 
care should be exercised not to lay the rod in 
any metal filings which may be on the work 
bench, or to fasten it in the metal jaws of a vise 
unless protected by wood, cloth, or paper. If 
any small metallic filings become imbedded in 
the surface of the aluminum, then the film of 
aluminum oxide which forms and breaks down 
again with every reversal of the current when 
the rectifier is in operation, will not be com- 
plete at that point. In operation, this failure 



Pb 

Cathode) 




Al 

--\ Anode) 



, ^ Seal with 

parafin 



Collodion coating 
- 1/4" above and 
below surface of 
liquid 



FIG. 2 

The rectifying jar. Several of these cells go to make 
up the complete rectifying unit. The anode, 
cathode, and vent are supported in a cork top 



222 



Radio Broadcast 



110 V. 




FIG. 4 

The circuit of the chemical rectifier. Four jars are 
arranged in series-parallel to obtain the double- 
wave rectification which is properly smoothed out 
in the filter resulting in a direct current 

of the oxide film completely to insulate 'the 
aluminum electrode from the electrolyte will 
be indicated by tiny sparks appearing at the 
impurity. This type of sparking should not 
be confused with the general scintillating 
sparking caused by using too high a voltage 
across the rectifiers. Such sparking is due to 



the electrical breakdown of the insulating 
film of aluminum oxide and will begin to take 
place when the impressed a. c. voltage is 
over 1 60 volts. The aluminum electrode in a 
properly operating cell will glow with a pale 
yellowish-green light and there will be no 
sparking. A slight sparking does not, of 
course, make a cell inoperative. In order to 
prevent sparking and consequent consumption 
of aluminum at the surface of the electrolyte 
where a protective film is not formed, the 
upper part of the electrode is coated with 
collodion, as shown in the illustrations. A 
short length of glass tubing is inserted in the 
vent hole in order to prevent its closing when 
the stopper is squeezed into the bottle. 

Although there are several good solutions, 
I have found the two given below to be con- 
siderably superior to any others that 1 have 
tried. 

Though not very generally known, they 
were among the original electrolytes used by 
Professor Nodon in developing his "Nodon" 
Valve. (See list of references at the end of 
this article.) 

WHAT SOLUTION TO USE 

THOUGH not the better of the two, the sol- 
ution most easily obtainable is a saturated 
solution of ammonium borate. It is most 
easily prepared by the layman by adding sev- 
eral tablespoon fuls of ordinary boracic (or 
boric) acid, such as is to be found in the med- 
icine chest of every home, to a half quart of 
distilled water in a glass or china container. 
Add four tablespoonfuls of ordinary household 




FIG. 5 

The complete circuit diagram of the chemical plate supply from input to output. The dotted lines indicate 

the various subdivisions of the device, as follows: pilot filament, step-up transformer, chemical rectifier, 

filter. Usual engineering practise is used in this diagram referring to condenser capacities 



How to Make a Chemical Plate Supply Unit 



223 



liov. 




FIG. 7 

The three posts on the right are the output. An 
external resistance (variable) is connected between 
the +90 and +45 posts to obtain the detector voltage 

ammonia (the clear kind not the kind con- 
taining soap or borax). Shake well and let 
stand for several hours. The excess salt will 
precipitate on the bottom and the clear solu- 
tion is to be used in the rectifiers. 

The other, and better, electrolyte is a satur- 
ated solution of primary ammonium phos- 
phate. (NH4H2PO4). It is prepared by ad- 
ding enough crystals of primary ammonium 
phosphate to one-half quart of distilled water 
so that no more will dissolve and then using 
the clear solution after the excess crystals 
have settled to the bottom. 

The practice of adding sodium or potassium 
salts to the electrolyte in order to reduce its 
resistivity is not to be recommended, for it will 
pit and corrode the anode (Al). The pre- 
sence of sodium salts in any quantity will also 
cause the rectifier to give off an unpleasant 
odor after it has been in use for some time. 

Never add anything but distilled water to 
take care of the loss of electrolyte due to elec- 
trolysis and evaporation. Addition of dis- 
tilled water for every 400 hours of use will 
generally be sufficient unless an unusually 
large vent is incorporated in the cell. 

In order to prevent a short circuit when the 
negative B terminal of the set is grounded, 
which is generally essential in order to en- 
tirely eliminate all a. c. hum, and also to raise 
the a. c. voltage, it is necessary to provide a 
transformer in the 1 10 volt a. c. line. The 
standard 75 watt amateur c. w. type trans- 
former may be used for this purpose by run- 
ning it with a resistance in the primary circuit 
or by feeding the 1 10 volt winding with a lower 



voltage obtained from a toy step-down trans- 
former, in order to reduce the out-put voltage 
to a usable value. Such an arrangement is, 
however, both needlessly expensive and in- 
efficient. A bell-ringing transformer may be 
worked backwards from a toy step-down 
transformer. Another bell transformer can 
not, however, be substituted for the toy trans- 
former. Very satisfactory results were ob- 
tained by using an Acme i|-henry double 
choke as a transformer. One winding serves 
as a primary and the other as a secondary. 
The air-gap must be tightly closed. (Some 
choke coils have no air-gap.) This will, of 
course, be merely a "one-to-one" transformer, 
and due to the design, the voltage regulation 
is poor. 

HOW TO MAKE THE TRANSFORMER 

FOR best results, a transformer should be 
made which will meet the exact require- 
ments. As the cutting and rolling of silicon 
steel for transformer cores is a task which the 
average person will not care to tackle, the use 
of the core from a toy step-down transformer 
is recommended. These cores are well made, 
of the shell type, and of the right size. The 
only thing to be discarded is the low voltage 
secondary. Moreover, they may be pur- 
chased at very reasonable prices, the list for 
the one best suited for this purpose being but 
$3.75. A transformer should be selected 
which has a no-load power consumption of not 
more than ten watts. The transformer re- 
ferred to above and used in the current tap 
shown in the photographs meets all these re- 
quirements. It is the new model 40 watt 

K- 110 V.-- - 




Pb 




DC 

FIG. 8 

The single cell method of rectifying. A double trans- 
former secondary is necessary as the circuit shows 



224 



Radio Broadcast 



Condensers 



Pilot Lamp, 



45V. 




FIG. 6 

The wiring layout. This drawing should be compared with the circuit diagram in Fig. 5 to identify 
the several parts and also the internal circuits of the choke coil and the transformer. The voltage regu- 
lation will be from 120 to 90 and 45 1024, depending upon the internal characteristics of the transformer 



Lionel toy transformer. The task of removing 
the core will be greatly simplified if some al- 
cohol is first applied in order to dissolve the 
shellac which binds the core together. Re- 
move the low voltage winding and in its place 
substitute a secondary wound with No. 28 or 
No. 30 enameled copper wire. Insulate each 
layer with thin tough paper. Protect the new 
winding from the core and case with Empire 
cloth or other suitable insulation. The proper 
number of turns will be 1 125 for use with am- 
monium borate electrolyte and 1030 for use 
with the primary ammonium phosphate elec- 
trolyte. In either case, the final filtered d. c. 



voltage will be approximately 1 10 volts. For 
lower voltages use fewer turns. 

The fact that turning off the A battery 
switch on the set does not shut off the input 
to the power unit, makes it desirable to em- 
ploy a pilot lamp in order to remind one of 
the second switch. This lamp should be so 
connected as to burn whenever the power unit 
is turned on. A small-flash light bulb, or even 
an automobile type bulb may be used for this 
purpose. In order that its life may be long, 
it should be burned at less than rated voltage. 
It is to be fed from a separate transformer 
winding of a few turns of No. 20, No. 22, or 



PARTS REQUIRED 



2 Lionel transformers, 40 watts . . $7.50 

4 W. E. 2 mfd. condensers . . . . 3.60 

i pound No. 30 enameled copper wire . .88 

i Bradleyohm No. 10 2.00 

i Flashlight bulb and socket ... .20 

Steel box, panel, binding posts, etc. . 

4 3-02. "salt-mouth" bottles ... .20 

4 No. 6 rubber stoppers .20 

i 2-ft. length chemically pure alum- 
inum rod f 5 6 inch diam. .20 



i 2-ft. length lead rod iVinch diam. 
i 6-inch length jV outside diameter 

glass tubing 

i oz. NH4 H2 PO4 at 6oc 8 oz. . 



.20 

.05 

15 



Total between $ 15.00 and $16.00 

The lead and aluminum rods come in 2-foot 
lengths. This is more than required, but frac- 
tional parts of a bar are not sold. 



How to Make a Chemical Plate Supply Unit 



225 



No. 24 wire. The winding must be well insu- 
lated from the other windings. Ten turns 
will be right for a 3-volt flashlight bulb. 

If the output of the rectifier were to be fed 
directly into the radio set, a disagreeable hum 
would be heard in the loud speaker. The first 
step to be taken in the elimination of this hum 
is to pass the current through a filter before 
it reaches the set. The purpose of the filter 
is to "smooth out" the pulsations in the recti- 
fied current in much the same manner as the 



air dome on a reciprocating water pump 
" smooths out " the flow of the water. Where 
very large capacity condensers are employed in 
the filter circuit (such as described by Mr. C. J. 
Lebel in the September, 1924, RADIO BROAD- 
CAST) then a more nearly correct hydraulic 
analog would be a pump feeding a reservoir 
from Which a steady stream of water might be 
drawn. Filters of the reservoir type, while 
exceedingly effective, are needlessly expensive 
and cumbersome, so that the use of a filter of: 




RADIO BROADCAST Photograph 
FIG. 9 

The top is removed from the unit to show the construction. Either the transformer or choke coil should 

be shielded. In this model, the choke coil is shielded. This shield is grounded to the metal box which in 

turn is connected to the negative side of the output supply 



226 



Radio Broadcast 



the "smoothing" type, such as was described 
in RADIO BROADCAST for December, 1924, by 
Mr. R. F. Beers, is to be recommended for use 
with this B supply unit. (When an S tube is 
employed as the rectifying device, then it be- 
comes imperative to use the larger filter). The 
filter details are given in Fig. 5. The choke 
coil should have an inductance of about twenty 
henries and must be of fairly low resistance. 
The choke referred to in the December, 1924, 
RADIO BROADCAST meets these requirements. 

MAKING THE CHOKE COIL 

AN EXCEEDINGLY fine choke for use 
with this outfit consists of one pound of 
No. 30 enameled copper wire wound on the 
same type of core as recommended for the 
transformer. If No. 30 wire is used for the 
transformer secondary, then one pound of 
wire will be sufficient for both purposes, as the 



transformer will require only about an ounce 
of wire. The d. c. resistance of such a choke 
is but 320 ohms. Thus the voltage drop across 
the choke will be negligible. The use of audio 
frequency transformer secondaries as chokes is 
not to be recommended, because of their ex- 
tremely high d. c. resistance. (About 2500 
ohms for the average transformer secondary.) 
There have been many complaints about 
B substitutes whose output voltage varies 
considerably with different loads. Thus such 
devices might supply 90 volts to the plates of 
the amplifiers in a small two- or three-tube 
set equipped with proper C batteries, whereas 
they would not deliver more than forty or fifty 
volts when connected to a big "super," es- 
pecially if no C batteries are employed. Such 
difficulties will never be encountered with the 
current-tap described in this paper, owing to 
the extremely low relative resistance of the 




RADIO BROADCAST Photograph 



FIG. IO 



A metal pan for the jars keeps them in place and prevents spilling ot the electrolyte and the breaking of 
jars. A wooden sub-base allows the unit to be assembled first and then placed in the metal cabinet 



How to Make a Chemical Plate Supply Unit 



227 



choke and valves as well as the excellent vol- 
tage regulation of the shell-core transformer 
employed. 

DETAILS OF CONSTRUCTION 

'"IP HE next and almost equally important 

* step to be taken in the hum elimination is 
the grounding of the negative B lead from the 
B eliminator. This is very important! Be- 
fore doing it, however, examine the regular 
ground connection to your set and see whether or 
not it is on the opposite side of the A battery 
from the negative B. If it is, then a large fixed 
condenser must be connected in series with 
the regular ground lead or else it must be re- 
moved altogether. (We mean the ground to 
the set, not the ground to the power supply.) 
If both sides of the A battery were to be di- 
rectly grounded, the A battery would be short 
circuited. 

The third step is to insert C batteries in 
your set so as to reduce the tube space current 
to a minimum consistent with good quality. 

The fourth step is to shield the choke coil 
from the power transformer. I f they are both 
in the same metal box, then merely placing 
their cores at right angles to each other may be 
all that will be required, although quite fre- 
quently, it is necessary to place a grounded 
iron or steel partition between them, or even 
to place one of them in a separate metal box. 
The entire unit should be located at least 
three feet from the set. This 
is not always essential, espe- 
cially where the unit is thor- 
oughly shielded, but never- 
theless it is a good rule to 
follow. 

The fifth and last of the 
precautions to be taken is to 
remove as far as practicable 
from the set any lamp cords 
carrying house current. Oc- 
casionally when one fails 
completely to eliminate all 
the a. c. hum in a receiver 
using this B supply it may 
be due to ungrounded BX 
cables and conduits which are used in the 
house wiring. 

It might also be well to add that in regen- 
erative sets a large fixed condenser (^ to i 
m'fd.) must be connected directly from the 
plus detector B binding post on the set to the 
negative B binding post. This condenser 
must be located at the set and not several 
feet away at the unit itself. The small con- 
denser connected across the primary of the 




FIG. 12 

A dummy jar element 
unit showing how Fahne- 
stock clip binding posts 
of a special type can be 
used to connect to the 
elements. The support 
stopper is of rubber. 
The clips are so designed 
that they will slip easily 
over the anode and 
cathode tops 



RADIO BROADCAST Photograph 



first audio transformer in many such sets will 
not act as a substitute for the larger condenser 
connected as .explained above. All regular 
neutrodynes have a small condenser con- 
nected directly from the detector plate to the 
negative B which is sufficient in such cases. 
Don't, however, try such an arrangement on 
a regenerative set or it will cease regenerating. 
The small pocket voltmeters sold for testing 
B batteries are worthless for determining the 




RADIO BROADCAST Photograph 
FIG. I I 
It is neat in appearance and 



The finished product. It is neat in appearance and 
very convenient. The unit may be placed on a 
lower compartment of the same table as the radio 
receiver, unlike many unsightly home made plate 
current supply devices 



228 



Radio Broadcast 



voltage supplied to the set by a B substitute. 
If a milliammeter and some B batteries are 
available, then a fair method is to read the 
plate current when the power supply is being 
used, and then switch over to the B batteries 
and by varying the number in use, obtain the 
same plate current as with the power supply. 
The voltage of the B substitute is then roughly 



that of the B batteries, producing the same 
plate current. 

The cost of operating a power unit drawing 
approximately ten watts from the house cur- 
rent is $0.0009 per hour, Thus it costs but 
about ninety cents for one thousand hours of 
B supply and there is no shelf life deterioration 
when the set is not in use. 



GENERAL REFERENCES 



For the benefit of those who may desire to 
obtain further information on the interesting 
subject of electrolytic rectifiers, the following 
references are given: 



Vol. i 



Vol. i 



Transactions of the International 
Electric Congress of 1904 "The 
Nodon Valve," by Prof. Nodon. 
Transactions of The American 



trolytic Rectifiers," by Prof. Bur 
gess. 

QST: June, 1922, "Electrolytic Rectifiers 
for Amateur Transmitting Work," 
by S. Kruse. 

These references are mainly of a scientific 
nature and contain little constructional infor- 
mation which would help the builder of a plate 



Electro-chemical Society, 1902: "Elec- supply unit such as described in this paper. 




WILLIAM H. ECCLES 

Demonstrating at a lecture at the Imperial College of Science in London a circuit on which he has spent 
much time, which is to bring about a new method of wireless communication. The sending apparatus 
produces easily recognizable musical chords at the receiving station. The most common chords would be 
assigned to the vowel sounds. Dr. Eccles is Professor of Applied Physics and Electrical Engineering at 
the London Technical College and a well-known authority on radio 




Jby Carl Dreher 

Drawings by Franklyn F. Stratford 



Computing How Far a Radio Station Can Be Heard 



M 



R. HARRY L. BEACH of Bristol, 
Connecticut, referring to our article 
on the sos in RADIO BROADCAST for 
March, raises a pertinent issue. 
He writes as follows: 



While listening to the various stations each night, 
if I get KGO I am highly elated, having accomplished 
an extraordinary feat. On the other hand, if I get 
some little station in New Jersey, I never know 
whether to be elated or scornful. You have pro- 
posed an empirical formula for the interference 
caused by any station to a 6oo-meter signal. Can 
you produce an equally simple formula expressing 
some convenient unit of power or relative power 
available to me from a broadcast station, given its 
distance watts and frequency? Local conditions 
and 'the efficiency of my receiver make it impossible 
for me to compare directly with any other receiver, 
but if I knew I was doing as well to receive XYZ at 
200 miles as KGO across the continent I would have 
that "Grand and Glorious Feeling" more often and 
would worry less. 

A formula along these lines already exists, 
fourteen years old. It is the Austin-Cohen 
transmission formula, first reported in "Some 
Quantitative Experiments in Long Distance 
Radio Telegraphy," by L. W. Austin, in the 
Bulletin of the Bureau of Standards, Vol. 7, No. 
3, Page 315, arid reprinted in numerous places 
since. This formula gives the received cur- 
rent in terms of the current in the transmit- 
ting antenna, the effective or electrical height 
(which is only a fraction of the physical height) 
of both antennas, the wavelength, the dis- 
tance, and some exponential factors. The 



exponential factors may be neglected not 
because they are small, for as a matter of fact 
they are exceedingly great, but for the reason 
that distance reception is accomplished at 
those times when the absorption is slight, and 
the loss in signal is only that imposed by the 
simple inverse-wit h-distance law. In 'other 
words, the only time that a listener has a 
chance to make a distance record is when 
atmospheric conditions are such that the 
exponential factor approaches unity and does 
not figure in the problem. 

It follows that the ability of a station to 
reach out is expressed by its meter-amperes 
product, obtained by multiplying the effective 
height of its antenna by the amperes flowing 
in the ground lead thereof. Suppose 'we' have 
a typical 5OO-watt station with an antenna 
whose physical height above ground is 1 50 
feet (roughly 50 meters). The effective or 
electrical height might be half of that, or 25 
meters. The antenna current will be around 
8 amperes.: Hence the meter-amperes prod- 
uct is around 200. .Some. "mosquito" broad- 
caster might have an ampere in the antenna 
and a height of ten. meters electrically: he 
would rate only 10 in this scale. High power 
trans- and in.ter-contiriental radio telegraph 
stations range from 20,000 to 300,000 meter- 
amperes. 

The sporting factor sought by Mr. Beach 
might be very simply expressed as 

Distance in Kilometers 

DX Index = 

Meter-Amperes 



230 



Radio Broadcast 



The only trouble is that the Department of 
Commerce does not publish the meter-amperes 
product of broadcasting stations, although it 
asks for them in the license application. 
Worse, this product is seldom accurately 
known, because a rather intricate procedure 
is required to determine the electrical height. 
So, for practical purposes, we are more or less 
out of luck. A rough approximation would 
be simply to divide the distance in miles by 
the power in watts. The Department does 
print the ostensible power of the stations in 
occasional issues of the Radio Service Bulletin, 
a monthly publication obtainable from the 
Superintendent of Documents at twenty-five 
cents a year. On 
this basis, KGO with, 
say, 2,000 watts in 
the antenna, heard 
over a distance of 
3,000 miles, would 
have a constant of 
1.5. KMO, with 10 
watts, would have 
the same constant 
only 15 miles away. 
This looks as if there 
should be some 
weighting in favor of 
the higher powers, 
cutting them down a 
little. However, with 
the meter - amperes 
product unavailable 
the problem really 
passes out of the 
realm of engineering 
speculation. It re- 
minds me of a remark 
of Professor N. S. 




THE TIPPED MICROPHONE 



Giuseppe de Luca, baritone of the Metroplitan 
Opera Company, toying with a broadcasting micro- 
phone. When the microphone is placed in this 
position, it becomes practically inoperative 



stations will put a crimp in DX motives. But 
as long as little stations exist, they will have 
the function, not only of affording expres- 
sion to local talent and taste, but also of keep- 
ing the DX spirit alive, by giving its devotees 
an almost inaudible signal, smothered in noise 
nine tenths of the time, to shoot at. 

Signor De Luca Tips the "Mike" 

OUR illustration shows what happens 
when you let the artists run a station, 
or rather what would happen if they 
were allowed to run one. Here is Signor 
Giuseppe de Luca, one of the most talented 
of baritones, publicly 
tipping a carbon mic- 
rophone. Naughty, 
naughty! For, when 
a carbon transmitter 
is tipped at such an 
angle, it ceases to be 
a microphone. The 
carbon falls away 
from the diaphragm, 
and can no longer 
transform into elec- 
trical impulses the 
agitations produced 
in the latter by sound 
waves. Microphones 
of this type must be 
kept in the vertical 
plane if one intends 
to allow it to be acted 
upon by voice or 
music. But in a 



Shaler regarding the scientific value of spiri- 
tualistic manifestations, that it is like trying 
to make a topographic survey of the land of 
dreams. Besides, we have steered entirely 
clear of such factors as frequency. 

Nevertheless, the fact remains that our 
correspondent's idea is a logical one. The 
fault is in the rating of stations by power alone, 
neglecting consideration of the actual radiat- 
ing element, the antenna. If DX fishing is 
anything at all, it should follow that the 
smaller the fish, other things being equal, the 
greater the glory. It is therefore a unique 
sort of fishing, for all the followers of Izaak 
Walton boast of the great size of their 
catches; they love to stretch wide their arms 
and mouths when recounting their piscatorial 
exploits. The advent of real super-power 



photograph any mic- 
rophone one can 
find, is just as good 
lying down as standing up. 

Looking at the picture again, we derive an 
obscure but definite, anarchistic pleasure 
from it. We are so tired of upright micro- 
phones! They stand for good transmission 
or the devil to pay, for correct placing, proper 
vocal-orchestral balance, criticism, watchful- 
ness all the tribulations and strains of the 
job of broadcasting. But a slanting micro- 
phone there is freedom, a simian carelessness 
for consequences, a flinging of heels to the sky! 
It affects us like the spectacle of an orthodox, 
stout, and reputable citizen, reeling, in 
evening dress and hopelessly drunk, down 
Fifth Avenue on Sunday morning while the 
church-bells ring for all those who can hear 
them. Bravo for Signor de Luca and the 
publicity representatives! 



As the Broadcaster Sees It 



231 



The "Layer of Lines" Confesses 

IN THE New York Herald-Tribune for 
February 27th, "Pioneer," one of the 
bright constellations of radio criticism, 
writes: 

The lines from Schenectady to New York were 
blown down by high winds last night. That is why 
the comedy by the WGY players did not come as 
scheduled to the listeners at WJY. We wonder if 
this was not due in some measure to careless laying 
of the lines. 

"Pioneer" is a charming, conscientious, but 
non-technical lady; she has never straddled a 
cross-arm forty feet above ground in a howl- 
ing gale; the pole covered with ice, perhaps, 
and maybe a 30,000 volt transmission line in 
close proximity. In other words, she has 
never had the job of keeping an open wire 
circuit during bad weather. 

It happens that 1 am very intimately con- 
nected with WJY, in fact, I "lay" the lines. 
Whenever WGY and WJY are hooked up, I 
start out from Aeolian Hall in the afternoon, 
a reel of twisted pair twelve feet in diameter 
under my left arm, my mouth filled with car- 
pet tacks, and a sledge hammer in my right 
fin. Loping along at the pace of Mr. Nurmi, 
I pay out the line with inconceivable rapidity, 
dodging trains, automobiles, and dangerous 
animals, and here and there fastening the pair 
to a handy telegraph pole with a carpet tack 
and a blow of the hammer. I cross creeks, 
rivers, ridges, valleys, and mountains, keeping 
as straight a course as possible up the Hudson 
Valley. At about the same time a represen- 
tative of WGY starts south with the same 
paraphernalia and good intentions. We meet 
at Poughkeepsie, splice the wires, drink each 
other's health in a bucket of Hudson River 
water, and return to our respective stations. 

On the afternoon of February 26th, ob- 
serving the nasty weather, I fortified myself 
with three or four dozen drinks, prescribed 
by my physician, before starting out on my 
course. Something was wrong with those 
drinks, or else I did not have enough, for no 
sooner had I started than I perceived that I 
was not in my best form. I veered from one 
side to the other of Manhattan Island, missed 
the telegraph pole at Columbus Circle, strik- 
ing a traffic officer instead, and mashed my 
thumb instead of the carpet tacks in several 
instances. Nevertheless, after the fashion of 
heroic radio men, I persisted and made fair 
progress until the Harlem River was reached. 
I generally cross this by way of the Spuyten 



Duyvil bridge, because a pretty girl lives 
near the Bronx end of the viaduct and 
waves to me as I pass. Besides the girl, I 
always pay the tribute of a thought to the 
intrepid Dutch courier who perished here 
when he plunged into the flood, crying that 
he would cross "in spite of the Devil!" to 
warn the burghers of New Amsterdam of an 
Indian rising to the north from which episode 
the strait derived its name. All I can say is 
that I headed directly for the bridge. I 
missed it by fifteen yards, equivalent to about 
a foot for each drink. Maladetto diavalo, but 
the water was cold! And I had never drunk 
the Harlem water before. The mammoth reel 
of wire and the sledge hammer weighted me 
down. I thought I would meet the fate of the 
Dutch rider, and the channel would have to 
be renamed WJZ-WJY. How I struggled and 
yelled, churning up the waters of the Harlem 
like a steamboat, and bouncing my voice 
against the side of Inwood Hill. Suddenly 
something snapped. I thought it was my 
suspenders, but now I know it must have 
been the twisted pair. After epic exertion, 
I emerged on the north side of the river, and 
raced on to make up lost time. I flew past Yon- 
kers, Tarrytown, Ossining, where I glimpsed 
the warm and well-fed convicts at their eve- 
ning movie show, and Peekskill. Wet, frozen, 
and bedraggled, I staggered into Poughkeep- 
sie at 7 o'clock. My WGY colleague sat at the 
amplifier. 

"You're drunk and late," he said. 

"Yes," I wept hysterically, "but here are 
the pair!" 

We spliced the wires in silence, and began 
calling New York. More silence. New York 
did not answer. Then I realized that the 




I start out A*itli a reel of twisted poii 



232 



Radio Broadcast 



line was broken, grounded and crossed at 
Spuyten Duyvil. All was lost, including 
honor! And the next day "Pioneer" razzed 
us in her column. (A new critic has just been 
appointed and now rules in Pioneer's place.) 

The Memoirs of a Radio Engineer 

RADIO is different from all the engineer- 
ing arts, and has moved faster than 
any of the others in the last two dec- 
ades. That is my first excuse for printing 
these memories now, instead of waiting until 
I am seventy years old. In the second place, 
to wait until one is old, before writing anything 
of an autobiographical nature, is a disparage- 
ment of youth. If the experiences of youth 
are worth anything and they appear singu- 
larly precious to all but the most desiccated of 
men surely they are worth setting down at a 
time when they are still comparatively fresh 
in one's memory, when some vestige of feeling 
still clings to them. It is logical, therefore, 
to write one's memoirs in two sections, one 
at the age of about thirty, the other after one 
has passed sixty. The writing of this first 
section is what I now undertake, in somewhat 
the same spirit as that which impelled Max 
Beerbohm to issue his "complete works" at 
the age of twenty-four. 

Two objections remain to be disposed of. 
The writing of memoirs is, for presumably 
sound reasons, a prerogative of famous per- 
sons, and, indisputably, I am not famous. The 
answer to this is that such personages will 
appear in the narrative: I can be Boswell, if 
not Johnson. Furthermore, only the radio 
aspects of my career will be illuminated. The 
last suspicion of impropriety, that involved in 
the writing of such a history by a man still in 
the full tide of events, may be met by ter- 




^tfempi: 012 )her 



minating the story at a point sufficiently far 
back to allay the apprehensions of the in- 
dividuals and groups with whom I have 
fought so recently that they still remember it. 

These apologies and reassurances completed, 
the epic begins. 

In 1907, when I was about eleven years old, 
one of the elementary school teachers under 
whom I was incarcerated delivered to his class 
a lecture on magnetism, using for illustra- 
tion one of those small, flat, red-enameled 
horseshoe magnets which at that time sold for 
a penny in the stationery stores. At the same 
time he told the boys a cock-and-bull story 
about Mohammed's coffin, which, he alleged, 
was suspended between heaven and earth, 
without visible support, through the agency 
of magnetism. This instruction was not a 
part of the work of that class, I might mention; 
the teacher was endeavoring to amuse us, 
during an interlude, in reward for good be- 
havior. At any rate, the next day I bought 
one of these little steel magnets instead of gum 
drops, and amused myself magnetizing my 
mother's knitting needles. I also made an 
attempt on my father's watch, and, while I did 
not succeed in imparting to it any appreciable 
polarization, my efforts were not entirely in 
vain, for the watch stopped the same day. 
In my endeavors to suspend a miniature Mo- 
hammed's coffin between the magnet and the 
table I failed utterly. The armature either 
jumped to the magnet or fell to the table. 
After a time I gave it up and shot one of my 
playmates with an air-rifle. 

Shortly afterward I became interested in 
electricity. As yet I did not suspect that 
magnetism and electricity had any connec- 
tion. The first attracted iron; the second 
rang bells. I crawled around in a dark and 
dusty compartment under the stairs of my 
home, where the electric battery which rang 
the bells was located. This battery consisted 
of sal-ammoniac cells, each with a ponderous 
carbon cylinder and a zinc rod in a solution of 
ammonium chloride. Three such cells rang 
the bells of the house. Dry cells were very 
well known by this time, but their quality 
was not then good enough to push wet cells 
entirely out of the market. For the same 
reason, partly, the popular use of electric 
flashlights was practically unknown. The 
electrical industry has changed remarkably, 
even in these eighteen years. There were as 
yet no tungsten or other metallic filament 
bulbs, and most store windows in New York 
City were still lighted by Welsbach gas 
mantles. However, I was not yet interested 



As the Broadcaster Sees It 



233 



in the state of the electric industry. The 
Leclanche cells in the cellar represented, to 
me, a kind of magic. I did not know them by 
their correct name, of course, and in some way 
I got the idea that they were storage batteries. 
In due time I went to my parents and asked 
for a battery for Christmas. I had no clear 
idea of what I wanted to do with it, but I be- 
lieved that with a battery one might sustain 
and impart electric shocks and perform mis- 
cellaneous wonders. 

My father, then as now, was a business man; 
he knew nothing about batteries and cared 
less. However, apparently he realized that a 
battery alone would not serve my purpose. 
He bought me a small electromagnetic en- 
gine, a little wire, and three dry cells. This 
engine could be belted, with a rubber band or 
a piece of string, to a toy buzz saw which, on 
days when it was feeling good, could cut a 
matchstick in two. I operated this machine 
for hours every day, and soon ran down the 
dry cells. At this time I became acquainted 
with the odor of ozone, for the remarkable 
engine functioned with a make-and-break 
contact at which a fascinating blue spark 
flashed. All the boys in the neighborhood 
came to see the spark, to smell the ozone, and 
to have matchsticks cut in two. I received 
many flattering trading propositions in con-; 
nection "with "this possession a cannon eight 
inches long, a dog which the owner swore 
was capable of speaking several intelligible 
words, and a wagon with a soap-box body and 
iron baby-carriage wheels, being among the 
offers. All were declined. 

But, among children, as with their elders, 
the tendency is to grow tired of even the most 
precious possessions. After a few weeks, the 
excitement over the electric engine had died 
down, and it became necessary to seek new 
diversions. The engine had brought with it 
the catalogue of an electrical supply firm, and 
we began to study this. Such books are not 
only informing in themselves, but, to a boy, 
they bring up questions the answers to which 
he must seek elsewhere. What was a make- 
and-break spark coil, or a polar relay, and 
how did a burglar alarm work? Four or 
five of us began to inquire about these mat- 
ters, more or less urgently. We were lucky 
because an electrician lived in the neighbor- 
hood who had a much greater theoretical in- 
terest in his craft than is common; he did not 
consider us merely as nuisances, which we un- 
doubtedly were, but good-naturedly tried to 
answer our questions. But he was not our 
only source of information. In the public 




small Lqys carae io smell "the ozone 



D 



library we found perhaps a half-dozen books of 
the "boy-electrician" type, written expressly 
for aspiring juvenile experimenters like our- 
selves. They contained directions for build- 
ing voltaic batteries out of tin cans, tele- 
graph sounders constructed of wood and the 
vital parts of discarded electric bells, and even 
induction coils which could throw one-quarter- 
inch sparks. We devoured these volumes 
and pooled our money to buy wire and 10- 
cent-store tools. At the same time we were 
perfectly normal and primitive, we had fist 
fights, pursued the neighborhood cats with 
bean-shooters, and played baseball on the 
vacant lots. If any one had urged us to study 
electricity we should probably have resisted 
instruction violently. But, as no one cared 
one way or the other, we made fairly rapid 
progress. The main obstacle in our experi- 
ments was a well-known ailment of the human 
race: lack of money. 

Most of our energy, on this account, was 
taken up in finding substitutes for expensive 
materials. For instance, when I was twelve 
years old I built an electrophorus. This is 
an induction device for collecting posi- 
tive charges on a metal plate, usually of 
polished brass, held by an insulating handle. 
In its classical form it consists of an ebonite 
disc about a foot in diameter. This is elec- 
trified negatively by beating or rubbing with 
a piece of cat's fur. A metal plate of about the 
same size is set on top of the charged ebonite. 
The experimenter touches the top of the metal 
piece. This draws off the negative charge 
of the same, while the positive charge induced 
by the ebonite remains bound. The metal 
electrode is then lifted by the insulating 
handle. Now let the knuckle be presented 
to the edge of the metal disc, and a spark 
about an eighth of an inch long will leap to it 
with a slight stinging sensation. To me, this 



234 



Radio Broadcast 




workman prefers radio iowLisLey 



was an indescribably dramatic occurrence. 
Furthermore, by repeating the touch-and-lift 
procedure, one could draw sparks for hours, 
on a dry day, without the necessity of rubbing 
the non-conductor again. This puzzled me. 
It was not until years later that I understood 
that 1 had to work for each spark by over- 
coming the electrostatic attraction between 
the charged non-conductor and the metal 
plate. 

My electrophorus was not as aristocrati- 
cally constructed as the one described above. 
Instead of ebonite, I used beeswax and rosin 
in various proportions. I spent at least two 
months melting and remelting these ingredi- 
ents over the gas stove in my mother's kitchen, 
in one of her pie plates donated to the cause 
of science, in the hope of getting a spark 
a sixteenth of an inch longer than in some 
previous attempt. When the composition 
had cooled, I would flagellate it with a piece 
of flannel, and set on top of it a wooden disc 
coated with tin-foil, which had originally 
sheltered a piece of Liederkranz cheese. The 
handle was a stick of sealing wax. Nature, 
however, is impartial. With blind equity, she 
bestowed her electrostatic sparks alike on me 
and on the learned professors at Princeton 
and Johns Hopkins. 

(To be Continued) 

Blame It on Radio. II 

THE custodians of the art and industry 
of the theater, which, according to the 
eloquent Mr. Brady, is in process of 
ruin through the intrusion of radio broadcast- 
ing, may find comfort in the similar sad plight 
of other altruists. Other hearts are breaking. 
The British rum shops are emptied of custom- 
ers, the libraries are full of books which no 
one reads, the once lovely maids and matrons 
of Germany become the despair of beauty 



specialists. We reprint the evidence so that 
our readers may join in the universal lamenta- 
tion: 

PREFER RADIO TO WHISKY 

British Workers are more Sober, Salvation 
Army Finds 



LONDON, Feb. 26. The British workman of to- 
day prefers wireless to whisky and Bunyan to 
Barleycorn, Captain Charles Nicholson of the Salva- 
tion Army told the Finsbury justices at their meet- 
ing to consider liquor license renewals. 

" Drunkenness has been reduced by one half during 
the last few years," said the Captain, "and many 
public drinking houses are often empty on Sundaj 
evenings." 

New York Times, Feb. 27, 1925 

RADIO REDUCES DEMAND 
FOR LIBRARY BOOKS 



It has been said that the new and increasing in. 
terest in radio work has caused a falling off of interest 
in the libraries of England. The Middlesex Li- 
brary Committee reports that for November of last 
year there were over five thousand fewer books taken 
from the library than during the corresponding 
month of the year before. Even the work of the 
conference library was lessened by 20 per cent, dur- 
ing the same time. 

New York Sun, Jan. 16, 1925 

"RADIO WRINKLES" MAR FAIR 
LISTENERS' FACES 



By the Associated Press 



BERLIN 



Radio wrinkles are the latest bugaboo of German 
women, who see their faces marred by folds and 
creases brought on by the strain of listening to wire- 
less programs. Beauty specialists affect to find that 
the faces of female radio fans acquire a strained ex- 
pression from listening night after night to the radio. 

Their brows become knitted, their lips firmly 
pressed together and their whole expression har- 
dened and less womanlike, say the beauty experts. 
The consequence is what is called the "radio face," 
of which the chief characteristics are radio wrinkles. 
New York Herald-Tribune, January 4, 1925. 

As a professional broadcaster, practicing 
his art and mystery in the United States, I de- 
rive a certain comfort from the last item, 
which may be set against my grief at seeing 
the sum total of female pulchritude in the 
world diminished. May one not infer from 
this despatch that the German broadcast 
programs are even worse than the worst 
American efforts? 



As the Broadcaster Sees It 



235 



Oliver Heaviside 

HOW many people who own radio sets 
heard of, much less heeded, the recent 
death of Oliver Heaviside, referred to 
in the current issue of the Journal of tie A. I. 
E. E. as "an illustrious successor to Wheat- 
stone, Maxwell, and Kelvin." Probably not 
as many as would regret the passing of some 
self-styled radio expert who never did any- 
thing better than write meaningless letters 
after his name, revamp in disguised form the 
inventions of better men, turn out a few 
trashy magazine articles, and plug himself in 
the Saturday radio supplements. That is the 
way of the world. 

For Heaviside never tried, in the phrase 
of the day, to "sell" himself, to be popular 
and recognized. He was of the stature of 
the greatest figures of mathematical physics, 
and what he wrote was not adapted to the 
needs of the kindergarten or of the consumers 
of predigested mental foods. No editor of a 
tabloid newspaper ever printed his photo- 
graph beside that of some distinguished movie 
actress who had just shot her latest lover, not 
only because no tabloid newspaper editor 
ever heard of him, but also because few photo- 
graphs of Heaviside existed. In his reluctance 
to be photographed he resembled a great 
American, Henry Adams, a man of somewhat 
less originality but not dissimilar tempera- 
ment. 

Heaviside was an Englishman. He wrote 
occasional articles for the Philosophical Maga- 
\ine, the London Electrician, and other learned 
journals. He applied his mathematics, in 
which he was not much less adept than 
Newton or Leibnitz, to such problems as the 
propagation of electrical waves along wires, 
the distributed constants of telephone lines, 
and the development of the electromagnetic 
theory generally. His papers are inordinately 
hard to read. This being called to his atten- 
tion on one occasion, he answered sardonically 
that they were even harder to write. 

His work had very practical consequences. 
The fact is that the Armstrongs, the Poulsens, 
the He'isings, the De Forests, stand on the 
shoulders of the Maxwells, the Hertzs, the Ray- 
leighs, the Websters, and all the other dreamy 
investigators who live in a shadowy mathe- 
matical universe and write incomprehensible 
articles instead of selling real estate and trying 
to make enough money to buy a Packard. 
The engineers and inventors deserve all the 
credit they get, but it should not be forgotten 
that they owe their eminence and high visi- 



bility to the pure physicists who bear them up. 
In the case of Heaviside, it is a matter of 
common knowledge that Dr. Pupin's work in 
the loading of telephone lines was largely the 
conversion into physical facts of the British 
investigator's abstruse generalizations. The 
result was a clarification of speech and ex- 
tension ' of range on telephone circuits, re- 
puted, at the time, to be worth a few million 
dollars to the telephone companies, and 
probably second only to the development of 
modern equalizers and electronic repeaters in 
the expansion of the telephone art which 
includes radio broadcasting and the tying up 
of broadcasting stations by wire lines this last 
for the benefit of those radio listeners who 
don't see what Heaviside has to do with 
them. Pupin himself is a rare combination; 
he is equally at home as a mathematical 
physicist and as an engineer and inventor. 
He did not complain that Heaviside's articles 
required hard work on the part of those who 
read them; he did the work and collected his 
royalties. Personally, I am frank to say 
that I never had the brains to read Heaviside, 
but I have the sense to raise my hat. 

Heaviside was deaf all his life, and because 
of that and no doubt other causes he was as 
shy and seclusive as Darwin, who could not 
take an ordinary railroad journey without 
the most profound agitation. He lived alone 
in a small cottage in Torquay, which is in 
Devonshire on the English Channel. He was 
extremely poor, and in his last years subsisted 
on a pension of 200 a year. Nevertheless, 
he was seventy-seven when he died. There 
is nothing to show that he cared one way 
or the other about either circumstance. 
What could such ephemeralities mean to a 
Heaviside? 




stretch tieir arras and toasi 




SIMULTANEOUS OR TANDEM TUNING 



AMN something new that is not new 
has come up in radio. In Septem- 
ber, 1910, John V. L. Hogan filed a 
patent application for the "tuning 
of circuits." .The application stated that the 
primary object of the methods described was 
to render the manipulation of the tuning 
elements more easy and accurate. Mr. 
Hogan goes on to state the specific case of two 
or more tuned circuits having the same values 
of inductance (elec^ 
trically identical coils 
and wiring), shunted 
by the same capacities 
in variable condens- 
ers, which can be 
maintained in reson- 
ance (tuned to a com- 
mon wave), through- 
out the entire range 
of the circuits by 
varying the capaci- 
ties "similarly and 
simultaneously." 
Mr. Hogan suggests, 
"The component 

parts of capacities 2 and Cj (the two con- 
densers) can be mounted on the same movable 
support." This patent was granted twenty- 
eight months later. Twelve years afterward, 
several companies appreciating the possibili- 
ties of simultaneous tuning, built condensers 
with two or more sets of stator plates, and 
with the rotating plates mounted on a single 
shaft "the same movable support." These 
manufacturers were somewhat surprised to find 
themselves antedated by a decade and more. 
The experimenter who is seriously interested 
in this excellent arrangement will find in- 



Tbe Lab Offers You This Month 

ARTICLES ON 

Simultaneous tuning of two or more circuits 
with tandem condensers Pointers that may 
save you months of experiment. 
The second step in the Lab system of remedy- 
ing radio troubles. 

How to build an efficient and simple loop. 
A modification of the Knockout Amplifier. 
A safer and better way of connecting most 
loud speakers. 



valuable the theoretical considerations treated 
in Mr. Hogan's patent No. 1,014,002, and is 
strongly advised to study it. The enthusi- 
ast who does so will be less prone to fall for 
the incorrect arguments that prevail to-day 
among the advocates of simultaneous tuning. 
One of the principal misconceptions among 
these is the idea that any lack of matching in 
the coils can be compensated for by the use 
of verniers across the condensers. This is 
not the case, for if 
this is done, a balance 
is achieved only for 
one setting of the 
main condensers, and 
it is lost with the next 
variation of the tun- 
ing control. Sets 
employing such ver- 
niers take advantage 
of the simultaneous 
tuning effect only 
approximately, and 
the verniers in many 
cases are really sepa- 
rate controls. 

To achieve simultaneous tuning of two or 
more circuits the inductance values must be 
the same. Also, the capacity values must be 
the same and varied similarly. This last 
provision is not so difficult. Any condenser 
carefully constructed will have identical 
capacities (or sufficiently near to them) at the 
same degree of turn. The circuit-inductance 
discrepancies are more difficult to balance, 
and experiments in the R. B. LAB show them 
to be the real problem associated with simul- 
taneous tuning. These inductive differences 
are caused by the difficulty of winding r. f. 



In the R. B. Lab. 



237 



transformers to exactly similar inductance 
values, and the unequal effects of wiring which 
even the most scrupulous care will not always 
eliminate. 

Fig. i shows the conventional two-stage 
tuned r. f. circuit, with potentiometer con- 
trol, adapted to simultaneous tuning. It 
will be observed that the tandem condenser is 
used on the last two tubes, one stator to the 
second r. f. stage, the other to the detector 
secondary, and the common rotor shaft to the 
negative A battery terminal. A single con- 
denser tunes the first stage, r. f. Due to the 
presence of the antenna primary coil, which is 
generally closely coupled to the secondary of 
the first stage, the inductive discrepancies 
which we are endeavoring to avoid are gener- 
ally introduced in this coil. For this reason a 
single control (one shaft and three rotors) is 
not advised in a first attempt at tandem tun- 
ing. ' Also, in the author's mind, a two con- 
trol set is the more logical and desirable ar- 
rangement. 

The grid leak is returned to positive side of 
the filament to provide the desirable detecting 
bias. 

The circuit should, it is needless to empha- 
size, be wired with care to maintain r. f. leads 
at similar inductive values, i. e., the same 
lengths and spacing from metallic parts. If 
the experimenter is successful in this, and the 
condenser and coils are matched, no further 
adjustments will be necessary, and Fig. i repre- 
sents the most simple and ideal arrangement. 




A neutrodyne stabilizing condenser, C2 is conveni- 
ent for correctly balancing the capacities of the two 
circuits 

Should the inductances, however, not be 
balanced as will probably be the case, they 
must be matched by additional adjustments. 
The simplest method is to apply copper shield- 
ing to the coil with the highest wave, a fact 
that can be located experimentally. This will 
lower the wavelength of that coil. Shielding 
is easily applied by rotating a disk (cut from 
^j-inch copper sheet) slightly smaller than 
the diameter of the coil, in the field of the 
coil as you would a tickler. Or, strips of the 
metal cut into semi-circles, can be clamped on 
the outside of the secondary, the width of 
which will determine the amount of inductive 
variation. 

If these experiments fail to result in satis- 
factory resonance throughout the entire 
tuning range, it is probable that the capacities 
are slightly off balance due to wiring, etc. 
This can generally be remedied by connecting 
a condenser designed for neutralizing circuits 



GO 




-8 +22.5 +90 



FIG. I 

Simultaneous tuning of the conventional r. f. cir- 
cuit. Note the grid condenser-grid leak connections 



238 



Radio Broadcast 




FIG. 3 

Type of "tandem circuit" sets experimented with in the R. B. Lab. Three circuits 
and one dial is considerably more difficult than the two control arrangement 



as suggested in Fig. 2. A condenser of this 
type consists of two separated metal rods, 
covered by a glass tube, over which is clamped 
a movable metal clamp. Moving the clamp 



or slide will throw the extra capacity to the 
correct circuit. 

Simultaneous tuning may be adapted to 
any form of circuit. Even three or four cir- 




RADIO BROADCAST Photograph 



FIG. 4 

Coils, transformers, and condensers are easily tested in respect 
to "opens" or break down with a small battery and ear phones 



In the R. B. Lab. 



239 



cuits can be controlled with one dial, if the 
arrangement is effected with expert nicety. 
With more than two stators, shielding is 
generally necessary between and around the 
stators to reduce undesirable capacity effects. 
Elementary shielding is illustrated in the 
single control set in Fig. 3. 

SHOOTING TROUBLE 
PART II 

WE DISCUSSED last month a logical 
and efficient system for locating the 
"trouble area," in the various cases of a re- 
ceiver becoming inoperative. When the 
difficulty has been located, the remedy is gen- 
erally obvious and simple. Running in the 
same order as the tests, the following are the 
logical curative processes: 

A BATTERY 

IF THE battery is found to be low, recharge 
it. Replace broken leads with new wire. 
Corroded terminals should be scraped, sand- 
papered, and coated with vaseline. Should 
hydrometer readings show a repeatedly low 
drop and short life in one cell, the battery 
should be taken to a dealer for examination. 
Rheostats can usually be repaired. 

B BATTERY 

Replace or short out low cells or batteries. 



Last Amp Tube 




111 Mfd 






+ 90-150 V 

FIG. 6 

A better way of connecting your loud speaker, 
without decreasing volume. This diagram offers 

several advantages 



AUDIO FREQUENCY AMPLIFIER 

JACK prongs and sockets bear the first 
inspection. Pressing up or down with a 
pencil or a strip of wood will locate a 
faulty spring, which may be permanently 
bent into place. 

The cure for broken connections in any part 
of the set is obvious. Knocking about the 
bus-bar with a pencil will often locate a break 
(generally at a soldered joint) which has be- 
fore eluded a painstaking search. 

Opens or breaks occasionally occur in the 
flexible leads to audio frequency transformers. 
Transformers and coils are easily tested for 
opens, with a small battery and a pair of re- 




OA- 
3 

OB + 
135-150 

FIG. 5 

The improved Knockout amplifier circuit. Volume control by the elimination of the transformer is 
effected by the rotary switch, and the extra A battery post facilitates the use of an 8-volt power tube 

in the last stage 



240 



Radio Broadcast 




RADIO BROADCAST Photograph 
FIG. 7 
The completed loop from the rear 



ceivers. (Fig. 4). One phone -cord runs to 
the battery, and the other to the winding under 
test. The remaining connection is from the 
winding to the battery. A loud click on break- 
ing the circuit indicates a perfect coil. Trans- 
formers can be tested while in the set. 

Terminal breaks can be soldered, but in- 
terior breaks in the transformer winding can- 
not be easily repaired. In a case like this it 
is much better to buy a new transformer. 

Impedances and resistances can be tested in 
the same manner, and should be replaced if 
defective. 

RADIO FREQUENCY AMPLIFIER AND DETECTOR 

OPEN circuit in wiring or windings in 
radio frequency transformers, can almost 
always be soldered with comparative ease. 
Potentiometers may be repaired or replaced 
according to the ability of the experimenter. 



Broken down bypass con- 
densers should be replaced 
with new ones. 

TUBES 

A BAD tube is generally 
incurable. Once in a 
blue moon a hard knock 
with a pencil will help 
matters, but a replacement 
is generally the only re- 
course. 

PHONES AND LOUD SPEAKER 

I EADS are simply replaced 
- and terminal breaks 
can be resoldered with res- 
in core solder. Breaks in 
the windings are best re- 
ferred to the manufacturer 
for repair. 

ANTENNA AND GROUND 

IF THE trouble is traced 
to the antenna or the 
ground, most of the rem- 
edies are obvious. If the 
antenna is down, there is 
but one thing to do. If the 
lead-in is short-circuiting 
against part of the building, 
the leads should be read- 
justed so that the proper 
tension is preserved. If 
there is a break in the 
ground lead soldering the 
broken connection or replacing the damaged 
wire will solve this problem. 

In the July RADIO BROADCAST, we will dis- 
cuss remedies for the receiver when it works 
poorly. 



F 



AN IMPROVED KNOCK-OUT 
AMPLIFIER 

IGURE 5 shows a modification of the 
Knockout amplifier described in the 
December RADIO BROADCAST. The 
essential variation of this diagram from the 
original circuit is switch "S," of the two-blade 
rotary type permitting the elimination of 
the transformer. This provides a desirable 
volume control in the many instances when 
the intensity delivered by the full complement 
of tubes is excessive. With the transformer 
out, the amplifier functions as two stages of 
straight resistance coupling. Because of 



In the R. B. Lab. 



this, best results will probably be secured by 
using a loo.ooo-ohm resistor as a coupling 
resistance in the first resistance-coupled stage 
rather than the 25o,ooo-ohm unit recom- 
mended in the original article. The sug- 
gested values hold for the remainder of the 
circuit. 

In Fig. 5 a further modification will be 
noted in the provision of a separate binding 
post for the positive filament terminal of the 
output tube. This provides for the use of a 
uv-2O2 or similar power tube in the last stage. 
This tube requires a lighting potential of 
eight volts for most efficient operation. 
When so used the six-volt leads run to posts 2 
and 3, while the eight-volt lead or tap is con- 
nected to post No. i. When six-volt tubes 
are employed throughout, posts i and 2 are 
birdged over. 

This amplifier may be added to any receiv- 
ing set, immediately following the detector or 
reflex tube. For additional details, the in- 
terested reader is referred to 
December, 1924, RADIO 
BROADCAST. 

A BETTER LOUD 
SPEAKER CONNECTION 

IN MANY cases, from the 
standpoint of general re- 
sults, it is incorrect prac- 
tice to connect the loud speaker 
directly in the plate circuit of 
the last or output tube of the 
amplifier. Such a connection 
is usually recommended by the 
manufacturer because of its 
simplicity. The improvement 
suggested in Fig. 6 is offered 
to the fan who has been grad- 
uated from his first book of 
instruction. 

The diagram represents the 
last stage of any amplifying 
system : resistance, impedance, 
or transformer coupling, and 
its output, the loud speaker. 
The additional parts required 
are the choke, "X", and the 
one - microfarad condenser C. 
Reactance "X" can conveni- 
ently be the secondary of an 
ordinary amplifying trans- 
former. It will be observed, 
and herein lies the variation 
from the conventional, that 
the loud speaker is not in the 



plate circuit proper, but its place is taken by 
the choke coil. The audio results are of the 
same intensity as those outputted by the more 
usual arrangement, with the following ad- 
vantages: 

Only alternating current, the sound- 
producing variations, passes through the 
speaker windings. This removes the stress 
of a strong magnetic attraction on the dia- 
phragm, a strain that often results in a 
rattle when strong signals are coursing 
through the windings. The loud speaker 
windings are also safeguarded from induced 
surges when the plate circuit is suddenly 
opened, or the stress resulting from short- 
circuited tube. 

There are, however, a few loud speakers, 
especially designed for inclusion in the direct 
plate circuit, and which work better in that 
position. These instruments generally place 
importance on the polarity of connections. 
In Fig. 6, no consideration is given to polarity. 




FIG. 8 



RADIO BROADCAST Photograph 



The center construction of the loop. Any convenient 
wire below No. 20 can be substituted for the braid 



242 



Radio Broadcast 




RADIO BROADCAST Photograph 
FIG. 9 
An attractive and efficient coil antenna 



A UNIQUE LOOP 

MANY descriptions of receiving sets 
take the loop a little too much for 
granted, merely specifying it as the 
correct antenna, and leaving the details to the 
imagination of an often inexperienced radio 
constructor. The loop pictured in Figs. 7, 8, 
and 9, will function very satisfactorily on all 
loop receivers and will cover the broadcast 
band when shunted by a .00035 mfd. variable 
condenser. Its form is somewhat unique and 
its qualities excellent. The following parts 
were used in making this loop: 

6 pieces of Formica, or hardwood, 12 inches long, 

f inch wide and j> 6 inch thick. 
i piece of Formica cut in the shape of a hexagon, 

4 inch from face to face and -fg inch thick. 
I piece of brass tubing or rod 20 inches long and f 

inch in diameter. 



100 feet of Springfield i6-strand braided copper, 

made at Springfield, Mass. 
121 brass round head machine screws, /.> or f , and 

\ inch long. 
10 brass round head machine screws -^ and f 

inch long. 
2 brass round head machine screws ^ inch and 

1 1 inch long. 
2 brass washers about f inch thick and with a hole 

in them large enough for the -fc machine 

screws to go through. 

Any convenient wire can be substituted for 
the braid. No. 18 annunciator wire will 
probably give quite as good results, though ap- 
pearances may suffer slightly. 

The bottom spoke of the loop should have 2 1 
holes threaded in it with an -fa or -^ tap, 
beginning one half inch from the outside end 
and spacing the holes one half inch toward the 
inside end. The remaining five spokes have 
only 20 holes beginning one half inch from 
the outside end. From the inside end of all 
six spokes tap two holes, the first f of an 
inch from the end and the second if inch on a 
line through the center. 

The rest of the story is told in the photo- 
graphs. Fig. 7 details the control 
construction and the manner of 
winding. Fig. 8 is a rear view of 
the complete loop, which Fig. 9 
shows in operation. 

COLDERING has been a problem 
^ of the radio fan for some time. 
The acid fluxes and pastes that 
facilitate a creditable joint in the 
more strenuous trades are taboo in 
radio construction. Acid corrodes 
the delicate wires, and, like the con- 
ventional pastes, works its way into 
places where it introduces leaks 
with accompanying noises. The R. B. LAB 
has had great success with an excellent non- 
acid soldering fluid manufactured and sold 
by John Firth and Company, New York 
City. 

THERE are four or five different sizes of 
B batteries available to the radio experi- 
menter, and it is often a puzzling question as to 
which size is the most economical in the long 
run. The ultimate economy is determined by 
the number of tubes, and where the batteries 
are to be used (r. f., a. f., etc.), B battery volt- 
age, C battery, and the amount of usage and 
the individual characteristics of the tubes 
themselves. 

If you replace your B batteries more often 
than every three months, it will be profitable 
for vou to change to a larger size. 



Some Facts About Sound Waves 

How They Are Produced and How They Are Analyzed 
The Laws That Govern the Action of Sound 



BY B. F. MIESSNER 



COUND, as radio experimenters who have had a hand in developing communi- 
** cation by radio telephony have discovered, is a subject deserving of much 
study and experiment. Broadcasting, after all, is merely the transference of sound 
from a broadcasting studio to the listener. We are using radio means to accomplish 
this, and many devious electrical paths does the sound follow before it emerges from 
the loud speaker of the radio listener. A good broadcast engineer has to devote almost 
as much of his attention to sound as he does to the actual radio mechanics of its 
transmission. Mr. Miessner in these articles is attempting to tell the important 
physical facts about sound. In his first article (RADIO BROADCAST, for January, 
1925), he told of the importance of sound in the cosmic system and its particular 
relation to radio. His second article in the April RADIO BROADCAST was a dis- 
cussion of the basic physical facts about sound. This article continues the dis- 
cussion and includes some excellent photographs and diagrams of sound waves. 
This discussion of Mr. Miessner's, while somewhat technical, has a direct and im- 
portant bearing on radio broadcasting. THE EDITOR 



THE sound waves we hear are produced 
by minute variations in the normal 
pressure of the atmosphere. The 
crests of these waves are called con- 
densations, because in them the air is con- 
densed or compressed. In a graphical analysis 
they are shown as the positive halves of the 
wave graph. The hollows of 
the waves are called rarefac- 
tions, because in them the air 
pressure is lessened or rarefied; 
these in graphical analysis are 
shown as the negative halves 
of the wave graph. 

The actual variation in pres- 
sure constituting sound waves 
is very small indeed compared 
with normal pressure. While 
measurements of these varia- 
tions are very difficult to make 
because of their extreme min- 
uteness and fleeting nature, the 
most reliable results thus far 
indicate that the ear can hear 
a sound having an amplitude or 
pressure variation of only one 
one thousandth of a dyne per 
square centimeter. The actual 
pressure variation of the weak- 
est audible sound is about one 
part in ten billion in terms of 



the normal atmospheric pressure of nearly 
fifteen pounds per square inch. A pressure 
variation of one thousand dynes per square 
centimeter, which is one million times the min- 
imum audible variation, is painfully loud and 
represents the high intensity extreme ordinarily 
encountered. Extremely loud sounds then, 




FIG. I 



A photograph showing the reflection of a circular water 
wave by a plane surface, such as a straight sea wall 



244 



Radio Broadcast 




FIG. 2 

The photograph shows the reflection of a circular 
water wave by a curved surface as a curved sea wall 

are produced by pressure variations of only one 
ten thousandth part of the normal atmos- 
pheric pressure, or, in actual pressure, about 
.0015 pounds per square inch. There is no 
pressure gauge which will measure such small 
variations of pressure. Some indication of 
the delicacy and sensitivity of the human ear 
may be gained by these facts. 

SOUND WAVE PICTURES 

DHYSICISTS have long used a kind of 
* topographic map to indicate the sound 
waves in a given locality. As the 
civil engineer shows high lands 
by closely spaced lines and low 
lands by widely spaced lines, and 
connects all points of equal eleva- 
tion by these lines, so the phys- 
icist has used such lines to indi- 
cate the regions of high and low 
pressure forming the condensa- 
tions and rarefactions of sound 
waves. The actual photographs 
of spark waves published in a 
previous article of this series 
(RADIO BROADCAST for April), 
show these same effects very 
clearly and beautifully. Refrac- 
tion shadows of water waves also 
show them very clearly. 

As the result of much experi- 
ment, the writer has succeeded in 
developing an exceedingly simple 
method of producing and photo- 
graphing water waves, which illus- 



trate perfectly the effects of sound waves 
and the laws determining their behavior. 
Several of these photographs are repro- 
duced herewith, and numerous others will 
be used in succeeding articles. 

While these representations of sound 
waves are valuable in aiding the under- 
standing of acoustic phenomena, and par- 
ticularly in tracing qualitatively the effects 
of reflection, refraction, absorption, diffrac- 
tion, and other important characteristics, 
a more accurate method is necessary for 
quantitative representation and analysis. 
If we take an instantaneous cross section 
of a simple water wave, we may get a pic- 
ture like that shown in our illustration. 
Such views of waves may be obtained in 
aquariums, where a plate glass window 
constitutes one side of the tank, and per- 
mits observation of the fishes inside. The 
wave is seen here as variations of height 
from point to point above and below the 
normal water level. 

If we place a pressure measuring device at P 
and measure the pressure of the water at that 
point at equal time intervals as the wave 
passes overhead, we may construct a curve or 
graph with rectangular coordinates, which 
will show the variations of pressure with time, 
as the illustration shows. If the point P 
moves downwards, thus increasing the normal 
or steady pressure of the water, the axis of the 
curve will move upwards, and vice versa, but 
the wave itself will remain unchanged, being 
shifted up or down accordingly. The vertical 




FIG. 3 

How a circular water wave is absorbed without reflec- 
tion by an inclined surface such as a sandy beach 



Some Facts About Sound Waves 



245 



lines or ordinates represent pressure, the hori- 
zontal lines or abscissae, represent time. Such 
representations of waves, or in fact any kind 
of variation, are quite common and serve a 
very useful purpose in study and analysis. 

THE PHYSICAL CHARACTERISTICS OF SOUND 

COUND waves, like alternating currents, 
^ are classified and described physically 
according to amplitude, frequency, length, 
and form. 

Amplitude. The amplitude of a sound wave 
refers physically to the actual increase above 
or decrease below the normal atmospheric 
pressure at the crest or hollow respectively. 
It is usually expressed in terms of dynes per 
square centimeter although for convenience, 
any other units of force and area may be used. 
The amplitude is related to the volume or 
loudness of a sound. But while the loudness 
increases with the amplitude, the relation 
between them is not simple or linear. The 
loudness is more closely related to what the 
physicist calls the energy of the vibration. 
The physical energy of a simple vibration is 
proportional to the square of the amplitude. 
This expresses a general law true for all kinds 
of vibratory energy. To illustrate: If several 
similar waves have amplitudes of one, two, 
and three, their respective energies will be 
in the ratio of one, four, and nine. 

While the physicist must use such interpre- 
tation in his study of the physics of sound, the 
psychologist knows that the ear does not re- 
spond with a loudness sensation strictly 
proportional to the physical energy of the im- 
pressed sound. There is a general law familiar 




- Water p 




FIG. 5 

Waves of similar frequency, but of differing ampli- 
tudes. This drawing shows that the energy of a 
simple wave is proportional to the square of the 
amplitude, the frequency remaining constant 

to the psychologist as Weber's law, which has 
been verified approximately for most of the 
senses, and which states that the sensation 
produced by a sense stimulus is proportional to 
the logarithm of the physical energy of that 
stimulus. That is to say, if the loudness of a 
given sound be increased from i, to 5, to 10, 
the actual energy would be increased ac- 
cordingly from i, to 150, to 22,500. The 
corresponding physical amplitudes would be 
the square roots of these latter values, or, i, 
12, and 150. 

This law, while not accurately true, and 
varying considerably for 
different ears, is neverthe- 
less important and must 
constantly be borne in mind 
in radio. For example, if a 
loud speaker must be made 
to give five times as much 
sound intensity or volume, 
it must be provided with 
about 1 50 times as much 
energy in its actuating cur- 
rent! 



Screen ; 



FIG. 4 

A sketch of a water wave as seen through the glass side of a tank, 
showing the wave in cross section. If one view the wave on one 
side through a cross section screen as indicated, with its lower left 
hand corner on P, the wave appears as a graph on the rectangular 
coordinates. Moving P and the screen up and down merely moves 
the curve oppositely on the chart without changing the wave form 



SOUND WAVE FREQUENCY 

THE frequency of a 
sound wave, like the 
frequency of any other 
wave, may be stated as the 
number of similar waves 
passing a given point in a 
second. The term wave de- 



246 



Radio Broadcast 



notes a compression and a rarefaction. Fre- 
quency in general terms refers to the pitch of a 
sound. Grave or low-pitched sounds are low 
in frequency; shrill or high-pitched sounds 
are high in frequency. 

The lowest sound on a piano tuned to inter- 
national pitch is 27 vibrations per second; 
middle C is 259, and the frequency of the 
highest sound is 4138 cycles, or double vi- 
brations, per second. Fig. 6 shows a piano 
keyboard tuned to international pitch and the 
corresponding sound pitch and wavelength of 
each key. The piano is thus an extremely 
valuable frequency standard for use in deter- 
mining by comparison the frequency of any 
musical sound. While not so accurate and 
unchanging as a set of tuning forks, it is never- 
theless a very convenient and fairly accurate 
standard which is available in almost every 
home. The piano strings, of course, sound 
many overtones, so that each key actually 
produces a number of sounds besides the 
lowest or fundamental vibration. These are 
exact multiples of the fundamental. I nasmuch 
as the fundamental tone characterizes the 
pitch as we hear it, we need not concern our- 
selves with the overtones in such pitch 
comparisons for determining the vibration 
frequency of some other sound source. 

The normal human ear will detect sounds of 
frequencies as low as 16 and as high as 20,000 
cycles per second. The actual limiting fre- 
quencies depend largely on the intensity of the 
sounds themselves, the limits extending with 
the loudness of the test sounds; for example, 



with very weak sounds the limits might be 20 
to 15,000 cycles for very strong sounds 12 to 
25,000 cycles. 

SOUND WAVELENGTH 

THE length of a sound wave is the distance 
between successive waves measured from 
corresponding points. If the frequency be 
known, the wavelength may be computed by 
dividing the frequency into the velocity of 
propagation. Thus, a sound having a fre- 
quency of 100 double vibrations (cycles) per 
second has a length of 1090 divided by 100, 
or 10.9 feet. 

In general, these relations are represented 
by the equation V = NL, where V is the 
velocity, and L the length of the wave. By 
using V = 300,000,000, the velocity of radio 
waves in meters per second, N in cycles per 
second, and L in meters, the wavelength or 
frequency of any radio broadcast wave may 
be computed similarly, providing one of these 
factors be known. 

The loudness sensation of sounds having 
the same physical amplitude but differing in 
frequency (i.e., wavelength), is not the same. 
It requires a much greater amplitude in low 
than in high tones to produce a given loudness 
sensation. This curious fact may easily be 
observed in a piano. The large, low-toned 
strings move visibly and strangely with a circu- 
lar kind of motion, the higher strings vibrate 
less visibly, and the very highest cannot be seen 
to vibrate at all. And yet all of the strings 
emit sounds of about the same loudness. 



I! 



00 (ji 



O tO M *> CT> ~vl VO 

us in ro co -u -si 



_ . to ro {* oo co oo 

10 o cr> 01 oo 01 oo 



00171 ID ~j-vj 



roro 
oooto 
coaiO 



orv> 
vooo 
010 



N>N> 
t 

IDCTi 



rou> 

VON) 

toco 



FIG. 6 

The frequencies and corresponding wavelengths of the sounds produced by the keys on a piano 



Some Facts About Sound Waves 



247 



The physical law, true for all vibratory 
energy, states that the energy of the vibration 
is proportional to the square of the frequency, 
the amplitude remaining constant. To illus- 
trate: Three sounds having equal amplitudes 
but unequal frequencies such as 100, 200, and 
300, would have physical energies in the re- 
lation of i, 4, and 9. The actual perceived 
loudness, however does not follow this physical 
law closely. While a detailed analysis of the 
perception of sound is not properly a part 
of a physical discussion, and will be reserved 
for a later article, it may be stated in passing, 
that, for equal energies the ear hears very high 
pitched sounds louder than very low ones, 
and mid-range sounds louder than either high 
or low. We can hear sounds of wavelengths 
between about 68 feet (i.e., 16 cycles) and 
0.65 inch (i.e., 20,000 cycles). When both 
the amplitude and frequency vary, the energy 
is proportioned to the product of amplitude 
squared and frequency squared. 

THE WAVE FORM OF SOUND 

THE only form of wave thus far discussed 
is that of the simplest possible type which 
is known as the curve of sines, or more gener- 
ally as a sine wave. Its mathematical 
derivation need not be introduced here. This 
type of wave in sound, while valuable as a 
basis for analysis, is really an extremely rare 
phenomena. 

The sine-wave sound is called a pure sound 
or tone, meaning that it consists of but one 
vibration frequency; it has no overtones. 
The purity of a tone refers to its freedom from 
overtones, and not to any aesthetic quality 
which this expression is sometimes meant to 
convey. A pure tone is extremely uninterest- 
ing musically. 

The sounds of nature, of music and of 
speech, are always relatively complex in this 
sense. Your voice in speaking or in singing 
what you think is a single tone may consist 
of twenty-five or more component simple 
tones, extending upwards in frequency from 
the fundamental or lowest frequency vibration 
to the highest overtone detectable by the 
human ear. A few musical instruments, such 
as the flute, the French horn, and certain types 
of organ pipes, can be made to produce nearly 
pure sounds, in which most of the emitted 
energy is concentrated in one frequency, 
but a few weak overtones are always present. 

Complex sounds consisting of many com- 
ponent partial tones, do not have the simple 
wave form of the pure sound. Instead, the 
wave form, like the sound itself, is very com- 




FIG. 7 

Waves of the same amplitude, but of differing fre- 
quency. The energy is shown here as proportional 
to the square of the frequency when the amplitude 
is the same 

plex. Fig. 9 shows such a wave form repre- 
senting the complex sound of a single organ 
pipe. The frequencies, amplitudes, and ener- 
gies of all the partial simple tones in this sound, 
as tabulated, completely describe the sound 
itself, except for what is known as the phase 
relations of the components, which is a matter 
of secondary and even doubtful importance. 
The energy column is calculated from the 
other two. The sum of the energies of the 
separate component partial tones is the total 
energy of the whole sound. 

FINDING THE WAVE FORM OF SOUNDS 

THE wave forms of various sounds can be 
photographically recorded by an instru- 
ment known as the oscillograph. The electri- 
cal oscillograph when used in conjunction with 
special microphones and amplifiers such as 
are now used in high-quality broadcasting, 
will produce a visual moving picture or a 
photographic record of the wave form of any 
sound impressed on the microphone. 

Professor Dayton C. Miller, of the Case 
School of Applied Science, about ten years 
ago devised a remarkable type of sound 
oscillograph which he calls the "Phonodeik." 
This ingenious instrument permitted him to 
record the wave forms of many different types 
of sound and to analyze their records at 
leisure. By his skillful mathematical calcula- 
tions, the slight distortion of the instruments 
could be corrected and the true wave form of 
the recorded sound developed. 



248 



Radio Broadcast 




frequencies and amplitudes of all the com- 
ponent partials. This may be done by a 
rather laborious mathematical calculation 
using the Fourrier equations, or an instrument 




FIG. 8 

Waves whose frequency and amplitude are both 

different. The energy is here shown as proportional 

to the product of the amplitude squared and the 

frequency squared 



Once the wave form is obtained, it is possible 
for sounds with only harmonic components 
(tha,t is exact multiples of the fundamental 
frequency) to analyze the wave and to de- 
termine exactly what simple waves it contains; 
it is further possible to determine the relative 





FREQ. 


AMP. 


ENERGY-N^ 


Fundamental =lst Partial 


100 


32.0 


104.0 


2nd " 


200 


22.0 


194.0 


3rd " 


300 


13.0 


152.0 


4th " 


400 


7.0 


78.5 


5th " 


500 


3.5 


30.6 


6th " 


600 


3.0 


32.4 


7th " 


700 


2.0 


19.5 


8th " 


800 


4.0 


102.0 


9th " 


900 


2.0 


32.0 


10th " 


1000 


1.5 


22.5 


llth " 


1100. 


1.0 


12.1 


12th " 


1200 


1.0 


14.4 



FIG. 9 

The complex sound wave produced by a single organ 
pipe. Its harmonic analysis gave the table of 
simple tones which provides an accurate physical 
description of the sound itself. The wave was ob- 
tained by Professor Dayton C. Miller of Case School 
of Applied Science, Cleveland, with his "Phonodeik" 




FIG. 10 
Professor Miller's "Phonodeik" which records the wave form of sounds 






known as the Harmonic Analyzer may be 
used (based on the same mathematical laws) 
which traces the curves of all the partial 
tones directly. 




FIG. A 

Through an error, the spark wave photographs pub- 
lished on page 1061 in Mr. Miessner's article, "The 
Physics of Sound" in RADIO BROADCAST for April 
were printed so as not to show the actual waves 
themselves. Figs. A, B and C, are reproductions 
showing the circular shadows of the spherical waves 
of condensation (dark), and rarefaction (light) pro- 
duced by an electric spark behind the central black 
disc. This, Fig. A, shows a curved wave striking a 
soft felt pad without reflection. Here the wave in 
the felt is being absorbed and converted into heat 




FIG. B 

Here the large circle is the shadow of an expanding 
spherical wave. These photographs are presented 
through the courtesy of the Riverbank Laboratories, 
Geneva, Illinois 



249 

By means of such a process of recording and 
analysis, the mixture of simple tones in musi- 
cal sounds can be determined just as the 
optician can determine with the spectroscope 
the various light frequencies present in any 
particular light emitted by a given light source. 

Not only this, but even more remarkable 
things can be accomplished. With such an 
analysis of any given sound as is shown in Fig. 
9, the physicist, like the artist who mixes 
numerous colors to produce the particular 
shade he desires, can synthetically produce the 
same kind of sound. To do this he produces 
simultaneously the component pure tones of 
correct frequency and amplitude, as deter- 
mined by the analysis, using electrically 
vibrated tuning forks or stopped organ pipes. 
Almost any kind of musical sound can thus be 
imitated with practically perfect completeness. 




FIG. C 

The wave here shown is being reflected with reversed 
curvature from a hard, flat surface. It shows the 
reflection or "echoing" of a spark sound at the 
surface of a hard body. These photographs are 
very unusual ones, even though from a photographic 
point of view they may appear to be slightly hazy. 
The poor appearance of the negatives is due in no 
part to poor photographic technique, but it is wholly 
the result of the extreme difficulty of the subject 

The modern pipe organ is one of the finest 
examples in which these principles are used. 
Dozens of different musical qualities or tone 
colors can be produced by control of the tone 
mixing stops on the manual. The "Telhar- 
monium" and the "Choralcello," in which 
similar effects are produced by electrically 
vibrated sounding bodies, have wonderful 
possibilities in this direction, but have never 
attained commercial development. 



The Better Receiver Contest 

Additional Information About Our Search for an Improved Receiver 
for Home Construction A Prize of $200 for the Design of a Better Set 



A EX PLAINED in the April maga- 
zine, RADIO BROADCAST, since its 
inception, has been endeavoring to 
present to its readers an abundance 
of up-to-the-minute radio information with 
special attention to exceptional receivers for 
home construction. Not content, however, 
with news alone, it has always been a policy 
that nothing be printed that was not an im- 
provement over that which had gone before. 
So it was that eventually the Roberts 
Knockout receiver was first presented to the 
radio field, and we have failed since that time 
to find a better circuit combining the various 
and singular attributes of this unusual set, 
although much effort and considerable money 
have been spent in this direction by the 
RADIO BROADCAST Laboratory. Members of 
our technical staff, combining a wealth of 
technical knowledge and experience, have been 
experimenting for the past eight months, but 
they confess that they are unable to improve 
the basic features of this receiver. 

Now what we should like to know is, Where 
can a better receiver be found? We confess 
we are beaten, and we are ready to pass the 
buck. The responsibility naturally devolves 
upon those to whom the radio field, in the 
final analysis, owes most, to those experi- 
menters and amateurs, engineers and what 
not, who have contributed development upon 
development, discovery upon discovery to the 
art of radio telegraphy and telephony. 

WHERE CAN A BETTER RECEIVER BE FOUND? 

DO YOU know of a better receiver? If 
you do write to us and tell us about it, 
or, better still, send us a set all hooked-up 
and we will test it in our Laboratory. If it 
is better than the Roberts we are willing to 
pay generously for an article completely de- 
scribing it and if it meets with the approval 
of those selected to serve as judges in this 
contest, we will mail you a check, not for $100 
as indicated in our April announcement, but 
for $200 which amount we consider more in 
keeping with the magnitude of the task which 
we have set before you. 

We remain unconvinced. We don't be- 
lieve that you can do it. Do you think you 
can? Then write to us and prove it ! 



The following specifications must be in- 
corporated in the desired receiver: 

1 . The receiver must not radiate. 

2. It may employ four tubes (or less if you 
think four are unnecessary). 

3. It must be extremely selective. 

4. It must be constructed to occupy a reason- 

ably small amount of space. 

5. It must be capable of operation with dry cell 

and storage battery tubes. 

6. It must be capable of operation with tubes 

operated at their normal filament voltage. 

7. It must be built to permit the transfer of 

tubes from one socket to another without 
materially changing the results obtained. 

8. It must produce good quality, without blast- 

ing or rattling on a cone-type loud speaker. 

9. It must be capable of satisfactory perfor- 

mance with several makes of parts designed 
for similar use. 

10. It must not require critical grid condenser 

or grid-leak adjustment. 

11. It must be simple to control. 

12. It must permit the use of voltage up to 120 
on the audio amplifier tubes (though less may 
be used if desired). 

13. The plate current consumption of the four 
tubes (measured at normal filament voltage) 
must not exceed 10 milliamperes when stor- 
age battery tubes are used. 

14. It must be capable of exceptional long- 
distance reception, with volume sufficient to 
fill a good-sized living room. 

15. It must be simple to operate. 

16. It must be free from hand capacity. 

17. Shielding must not be used. 

1 8. It must be capable of loud speaker opera- 
tion on two tubes. 

It will be noticed by comparing the above 
specifications with those contained in the April 
announcement that a few changes have been 
made. These changes have been considered 
necessary in view of the extreme difficulty of 
the task we have set before you, and they 
make the goal, on the whole, perhaps easier 
of attainment. 

Three judges have been appointed to de- 
cide impartially which is the better receiver 
yours or the Roberts. You will get a square 
deal at their hands. 

The conditions of the tests which we will 
give your apparatus remain as indicated in the 
original announcement. 

This offer is made, we repeat, only to those 



The Better Receiver Contest 



251 



who are interested in designing receivers for 
home construction. Later, if manufacturers 
of complete sets wish to employ a similar 
method of proving the excellence of their 
apparatus, we will have no objection, but in 
this particular contest only home built sets 
are concerned. 

Most of the letters received thus far present- 
ing us with descriptions of apparatus to be 
entered in this contest, have failed to comply 
with the conditions set forth above. We 
caution future participants that unless the 
rules governing this contest are adhered to, 



their communications will not receive our 
consideration. Many of our correspondents 
about this contest have failed to adhere to 
some one or more of the rules. The receiver 
to be entered must fit the specifications 
printed above. When you write us about 
your receiver, please condense your informa- 
tion as much as possible and take great care 
with the circuit diagrams. 

Now we ask again, Have you a better re- 
ceiver than we have discovered? We doubt 
it, but if you are sure you have, submit it to 
us and we will test it out. 




FITTING THE RADIO TO THE RADIATOR 

This photograph shows a receiver placed on a metal cabinet which fits over the radiator. Ordinarily, the ra- 
diator, especially in small homes and apartments is somewhat uneconomical, because the space it occu- 
pies cannot be used for anything else. The cabinet contains a humidor which moistens the air and the 
shelf is insulated which keeps it from absorbing heat. With this cabinet, made by the Dixie Metal Pro- 
ducts Company at Birmingham, Alabama, the radiator is made to do double duty. The new Farrand- 
Godley loud speaker and Carter self-supporting loop are also shown 




HTHE photograph in the lower left shows 
the receiver with the Lynch Lead ready to 
put in the automobile. The circle in the upper 
left shows how a potato can be used to de- 
termine the polarity of the battery leads. 
When the current is on and the bare wires 
applied to the potato, a green deposit forms 
around the negative wire which is then con- 
nected to the negative terminal of your receiver 





Take Your Radio Set to the 

\\ THEN your radio receiver goes on summer motor and camping 
W ent to take along storage batteries to supply the filament vol 
of the automobile furnishes six volts which is the proper potential 
of the tubes. The photographs on these pages show how the Lynch 
H. Lynch, editor of this magazine, can be used for connecting the 
to the radio receiver. The Radiola super-heterodyne is supplied 
the illustrations show how Brightson True Blue Power Plus tubes 
tery filament and a small base can be substituted in the "super." 

In the Radiola super-heterodyne, the dry cells which furnish 
considerably to the weight of the receiver. If the Lynch Lead is 
tomobile storage battery for the dry cells the "decreased weight of 
more portable an important consideration for summer radio. 

Any radio receiver, including all those described in this magazine, 
can be operated in this way from the automobile battery. The 
shows Mr. Lynch operating superheterodyne in- his automobile, 
loud speaker in use. 





upper cut shows John B. Brennan, Technical Editor 
of RADIO BROADCAST, substituting Brightson True Blue 
Tubes in the Radiola super-heterodyne so that it may be 
operated from the automobile storage battery. The center 
photograph shows the space left in the battery compartment of 
the "super" when the dry cell A batteries are removed 




Country ! 

trips, it is often inconveni' 
tage. The storage battery 
for supplying the filaments 
Lead, developed by Arthur 
automobile storage battery 
with three-volt tubes and 
which have a storage bat' 

the filament potential add 
used, substituting the au- 
the receiver makes it far 

with the use of this cord, 
photograph at the right 
Note the small Amplion 





A Simple and Inexpensive Unit Which the Home Constructor 
Can Easily Build It Can Be Applied to Any Type of Receiver 

BY A. O'CONNOR 



ANY number of radio users have tried for a long time to find a simple method of 
converting their present receivers to super-heterodynes. Nothing short of 
complete rebuilding has been the solution in the past. Up to now, there has really 
been no satisfactory method. The frequency-changer circuit described by Mr. 
O'Connor in this article is really a "canned" super-heterodyne which can be applied 
to any kind of a receiver except a super-heterodyne itself. 

Obviously there are two main avenues of endeavor which lead to the discoveries 
of real improvements in radio: those undertaken by commercial interests, and those 
in which the home experimenter plays the leading r61e. RADIO BROADCAST believes 
that it should present the best and most helpful material which may be developed 
by both types of radio investigators. We judge the material which is considered 
fortheeditorialpagesof the magazine by one measure: Will it help the reader? The 
fact that Mr. O'Connor falls into the commercial rather than the private investi- 
gator class has not influenced our policy in publishing this interesting and helpful 
article. THE EDITOR 



A^UPER-HFTERpDYNE of two tubes 
is not only possible but practical; any 
receiver now in operation may be 
made into a sensitive, selective super- 
heterodyne. With these two thoughts in 
mind, the writer began experiments over a 
year ago that brought the results outlined in 
this article describing a simple one-tube unit 
that will make a "super" out of any good re- 
ceiver, be it simple or complicated. 

Briefly, this unit changes incoming signals 
to a given frequency, just like the best of 
super-heterodynes, and the receiver that the 
listener now possesses acts as the "intermedi- 
ate frequency amplifier" that is such an im- 
portant part of present super-heterodynes. 
This unit is not difficult to construct, requires 
but little room, and uses standard parts that 
may be obtained generally. 

Such a unit will allow hundreds of thousands 
of listeners to have the benefits of the "super" 
at small cost and without discarding their 
present receivers. 

WHAT THE "SUPER" REALLY IS 

TO UNDERSTAND just how such a 
simple super-heterodyne may be con- 
structed it is necessary to delve a bit into the 
theory underlying this selective circuit. The 
"super" is really a frequency-changer, and 



this unit, described in RADIO BROADCAST for 
the first time is, simply, a frequency changer. 
In super-heterodyne receivers incoming fre- 
quencies are changed to some lower frequency, 
after which they are amplified by "inter- 
mediate-frequency" amplifiers and then de- 




FIG. 1 

The broadcasting band of frequencies is 820,000 
cycles wide and is represented here by taking a 
point on the circumference of a wheel and marking 
out its path as it rolls along the frequency line. At 
the end of one complete revolution the point has 
traversed 820,000 cycles. The smaller wheel 
representing the oscillator dial traces a similar path 
but in one revolution it traverses only 30,000 cycles. 
There are two points 60,000 cycles apart that a given 
station may be heard 

tected in the usual fashion. The lower fre- 
quency varies with different super-heterodynes, 
but usually is about 30,000 cycles (10,000 
meters). There are reasons why this frequency 



Making Your Receiver a Super-Heterodyne 



255 



may not be much lower, but few why it cannot 
be higher, and that is what is done in this unit 
where an intermediate frequency of about 
500,000 cycles (600 meters) is used. 

These lower frequencies are generated by a 
phenomenon called "beats" and are the result 
of compounding two waves of different fre- 
quency. As a concrete example, let us suppose 
the intermediate amplifiers are tuned to 30,000 
cycles and an incoming signal has a frequency 
of 750,000 cycles (400 meters.) Within the 
receiver is a frequency generator which we may 
vary until the difference between its frequency 
and that of the incoming wave is 30,000 cycles. 
At this point the intermediate amplifiers work 




r 50o,ooo~ 

K- 820,000~- 

* i.ooo.ooo 

FIG. 2 

By making the smaller wheel much larger, the path 
a given point on its circumference would trace out 
is longer. Before it completes two revolutions how- 
ever, it is outside the broadcasting band, and for this 
reason there will be only one point on the oscillator 
dial where a given station will be heard 

best and the signal will be passed along to the 
detector. 

This lower frequency may be obtained, in 
general, at two adjustments of the oscillator 
dial, namely, at the 750,000 plus 30,000 or 



780,000 cycles and 750,000 minus 30,000 or 
720,000 cycles. These two points correspond 
to 417 and 385 meters. 

Thirty thousand cycles is such a small per- 
centage of the broadcasting frequencies that 
the two points on the oscillator dial are always 
close to the value of the incoming frequency, 
although on the longer waves the two points 
are farther apart on the dial than at the low 
wavelength end of the dial. 

These two points are 60,000 cycles apart, 
and the action of tuning a given station at two 
points within the broadcasting band is some- 
thing like a small wheel revolving within a 
large one as shown in Fig. i . The small wheel 
may begin to rotate at any point, but at the 
end of two complete revolutions the same 
broadcasting station may be heard again. 
And since the present broadcasting band 
covers 820,000 cycles, it is apparent that there 
will always be two points on the oscillator dial 
for each incoming frequency if the inter- 
mediate amplifiers are tuned to 30,000 cycles. 

Suppose, however, that the intermediate 
amplifiers are tuned to 500,000 cycles. In this 
case, the same station will be found at two 
points 1,000,000 cycles apart, and since the 
broadcasting band is only 820,000 cycles wide, 
we may plan our coils and condensers so that 
the incoming frequency will be heterodyned at 
only one point on the oscillator dial. 

All we have to do now is to design an oscilla- 
tor that will beat at frequencies 500,000 cycles 
different from incoming frequencies. At the 
lower end of the broadcast wavelength band, 
220 meters equals 1,363,636 cycles and at the 



JONNOR FREQUENCY-CHANC 






RADIO BROADCAST Photograph 
FIG. 3 

Fhe panel view of the frequency changer. Simplicity and symmetry are the keynotes of construction and 
ayout. Due to the engraved indicators, the functions of the various control dials are self explanatory 



256 



Radio Broadcast 



other end of the broadcasting band, 550 meters 
corresponds to 545,454 cycles. To find the 
frequency of the oscillator to give us the 
required 5OO,ooo-cycle beat note, we must 
add to or subtract 500,000 cycles from these 
two extreme frequencies. Thus, 
220 meters = 1,363,636 cycles plus 500,000 cycles = 

1,863,636 
220 meters = 1,363,636 cycles minus 500,000 cycles 

= 863,363 
550 meters = 545,454 cycles plus 500,000 cycles = 

1,045,454 
550 meters = 545,454 cycles minus 500,000 cycles 

= 45.454 

Therefore an oscillator of the range 
1,863,636 to 1,045,454 or an oscillator of the 
range of 863,363 to 45,454 cycles would give 
the required beat frequency. These two os- 
cillators would cover wavelengths from 161 to 
287 meters or 348 to 6600 meters. Obviously 
the first one is the proper one to use. 

In this case there will be only one point in 



ing with the attendant howls and moans. 
Sometimes the upper point of station No. i 
interferes with the lower point of station No. 
3 which is on a longer wavelength; again we 
have heterodyning with the resultant dis- 
cordance, and we find that we are unable to 
get station No. i clearly on either of its two 
points. Such a condition is impossible with 
500,000 cycle beat frequencies, as it is im- 
possible to get a station at more than one 
point on the oscillator dial. 

With most "supers," the oscillator is con- 
tinually making an audible heterodyne with 
the incoming station as the dial is turned 
between the two points for the incoming 
station. This is because of the fact that 
half way between the two points it is actually 
on the exact frequency of the incoming sta- 
tion. With a 5OO,ooo-cycle beat frequency 
this is impossible as the oscillator always 
beats 500,000 cycles away from the incoming 
station. 





7 




c 








\ 
\ 

\ 




O 


Output 
d -^ .*-^-^-. . _^ 










^OOOOOCP m ? 

e^OOOOOpv . 1 II Jk 






( 


!o 2 
o 


VvUUvwl UD-H 

s^r : \ 
II I ^iim J 






( 


o 

K~~> 


HE f 1) -=- 






-| 


X ; 


\l ^ // ^~ 




i. 




S *~ 


7*" Al P 8 a*r "~~ 


c 


i 
fti 


?' 


o 

g 

^ i 


J-l 1' n Y"^ - g_ 




2 


a 


b 


SCHEMATIC DIAGRAM -H|ljlf+ 
A Battery 

a -Primary of pickle bottle coil g-. 00013 Fixed cond. * 
b- Secondary h- nnn^t; rAn/Honcor o/ivt <nQC> 



c- Tickler 

d- Oscillator plate coil 

e- Oscillator grid coil 

f -.0005 Condenser 247 F(Tuner) 



k -.00025 grid condenser 

m- 1 Meg.Leak 

n- 30 Ohm rheostat 



FIG. 4 

The schematic diagram of the frequency changer showing the Arm- 
strong system of securing local oscillations in the first detector tube 



the oscillator dial where a given station may 
be found as shown in Fig. 2. 

There is still another advantage in heter- 
odyning to 500,000 cycles. When heter- 
odyning to 30,000 cycles, it is quite often the 
case that the lower one of the two points for 
station No. i is in exactly the same spot as the 
upper point of station No. 2 which is on a 
snorter wavelength. This causes heterodyn- 



HOW YOUR PRESENT RECEIVER IS USED 

NOW that we have the 5oo,ooo-cycle 
beat note generated in our frequency- 
changer, it remains to provide an intermedi- 
ate amplifier tuned to this frequency, and 
here is where our receiver now in operation 
comes in. All that is necessary is to tune it 
to 600 meters (500,000 cycles) and to place 



Making Your Receiver a Super-Heterodyne 



257 




FIG. 5 



RADIO BROADCAST Photograph 



Looking down on the layout one clearly sees the general disposition of parts and the wiring 
scheme. The frequency-changer is really a very simple unit as this photograph shows 



Back 



Loop Ant. Gnd. A- A+ B+ Output 
Q Q Q Q Q Q O 




FIG. 6 

The wiring diagram of the one tube super-heterodyne showing the connections of the various units 




l-s 



M O 

.513 



. ,y 

H-o 



Making Your Receiver a Super-Heterodyne 



259 



its antenna and ground connection to the 
output of the frequency-changer, and we 
have a super-heterodyne. 

Fig. 4 shows the schematic diagram of the 
circuit and Fig. 6 shows the connection 
hookup. In Fig. 6, coils A, B, and C are the 



V- 






: i' 


tX) 






t V 




III 


J ^ 






*; 


r 






< - IB --> 






CONDENSER COUPLING UNIT 





FIG. 8 

To shield the condenser from body capacity effects 

it should be placed some distance from the panel and 

this coupling member enables the proper spacing to 

be carried out 

three windings of a three-circuit tuner, the 
primary (A) being untuned. Incoming sta- 
tions are tuned by the condenser F across 
the primary coil B. Their frequencies are 
heterodyned to 500,000 cycles by oscillator 
coils D and E, the latter coil being tuned by 
condenser G and H. Condenser G is placed 
in the circuit to increase the spread of the 
stations on the oscillator dial. The plate 
circuit, before it is introduced into the next 
tuning circuit, is brought into inductive rela- 



tion with the secondary tuning coil B, thus 
causing regeneration and increasing both 
volume and selectivity. The plate circuit 
now contains, among other frequencies, the 
desired frequency of 500,000 cycles, and is 
introduced into the receiving system, where 
it is tuned and rectified in the same way that 
a 6oo-meter station can be tuned in. 

You will note that in this arrangement, 
one tube receives and heterodynes at the 
same time. Up until a year ago this was not 
considered feasible, because tuning the oscil- 
lator circuit would detune the antenna cir- 
cuit, due to the two frequencies being so 
close together. Major Armstrong showed 
that it is possible, if the frequencies are quite 
a distance apart, and exhibited an ingenious 
scheme for using one tube while maintaining 
a low frequency intermediate wave. In the 
frequency-changer which we are describing, 
the two circuits are always 500,000 cycles 
apart and tuning one circuit has no effect on 
the other. In constructing the frequency- 
changer, the idea of low loss has been kept 
constantly in mind, and, by direct compari- 
son, low loss parts gave the best results. Dis- 
tributed capacity in coils was hunted down, 
and condensers of the highest type were used, 
the oscillator condenser being insulated from 
the hand by means of a good dielectric. The 
parts used are listed below, but of course 
equivalent parts can be used, always provid- 
ing that the constants are correct. 




RADIO BROADCAST Photograph 
FIG. 9 

This rear view shows clearly the disposition of the coils and other apparatus. Note how the oscillator 
coils are clamped between the two bakelite strips which are fastened to the oscillator condenser 



260 



Radio Broadcast 



ITEM 

/ 

2 



14 



75 
16 



18 



1 Formica panel 7 x 14 x T\ inches 

\ Baseboard 12 f x 7 x \ inches Poplar 

2 National Velvet Vernier 4-inch Dials 

i General Radio Switch Lever f-inch with two 

Contact Points and two stops 
i General Radio No. 301 Knob and Pointer; for 

use on the tickler coil. 
i General Radio No. 301 Rheostat 3o-ohm. 
i General Radio No. 247 F Condenser .00025 

mfd. logarithmic plates. 

3 f-inch Lengths Formica Tubing & inch 
o. d. T 8 s inch i. d. to space Item 7 from panel 

i Formica Coupling Member for Item 7 (Fig. 6) 
i General Radio 247F Condenser .0005 mfd. 

logarithmic plates 
35 inch Lengths Formica Tube fg inch o. d. 

fs inch i. d. 
i Eastern Coil Corporation Coupler, Broadcast 

Wavelength, (15 turns on tickler, with middle 

tap on primary) 

i King Socket R730 for uv-20 1 -A Tube 
i Dubilier Grid Condenser .00025 mfd. Type 

60 1 -G. 

i Daven Grid Leak .! megohm 
i Binding Post Panel complete with 9 binding 

posts 
i Oscillator Coupler as per Fig. 7; coupler in- 

cludes two coils as per description later in 

this article. 
Screws, wire, spaghetti, terminal lugs, etc. 



Total cost of the above parts should be between 
$35.00 and $40.00. 

Fig. 7 shows the actual drilling template 
for the panel, but of course changes must be 
made if other material is used. 

Fig. 8 shows a coupling member for the 



.ooo25-mfd. variable condenser. This in- 
sulates the condenser from body capacity. 
Item No. 3 in the list above covers three 
Formica tubes which are used to set the 
oscillator condenser back from the panel, and 
to line it up with the other condenser. Item 
1 1 covers spacers for the .0005 mfd. conden- 
ser. These are necessary because the design 
of the Velvet Vernier dial requires that the 
condenser be set back from the panel. 

The Eastern Coil Corporation coupler is 
known as a pickle-bottle coil, and has fewer 
turns than normal due to the fact that it is in 
circuit with the plate coil of the oscillator 
coupler. 

THE UNUSUAL OSCILLATOR COUPLER 

FIG. 10 shows the details of the oscillator 
coupler. This coupler is not the con- 
ventional type at all. In the usual coupler, 
the coupling between the plate and grid coils 
is fixed, and the coils are so large that their 
external fields exert an influence on all parts 
within a range of several inches. An at- 
tempt was made in this frequency-changer to 
design an oscillator which would have no 
effect on other parts, and this result was 
finally achieved. The coils shown have an 
exceptionally small external field, and the 
grid coil is placed 1 1 inches back of the oscil- 
lator variable .condenser, a position in which 
it has no effect on the condenser. The coils 
are known as "cross-wound," and have about 
as little distributed capacity as any coil 
known. The coils are wound on a f-inch 
core, are | inch thick, and each has 49 turns 



No.27Drill Drill and tap 6-32 No.27Drill 




COIL MOUNTING PART No.l 
3/i6 Formica Stock 



Drill and tap 






COIL MOUNTING PART No.2 
3^ 6 Formica Stock 



Part No.2 



Coils clamped between 
bakelite strips 

Part No.l 




- 6-32 Screws 



Brass Stock 



Solder lugs 

Part No.3- 

i 

COIL MOUNTING ASSEMBLY 



COIL MOUNTING PART No.3 
FIG. 10 



The details of the oscillator coupler are shown in this Figure. Small coils placed at some distance from their 
tuning condensers decrease the external field and the resultant coupling effects to other parts of the circuit 



Making Your Receiver a Super-Heterodyne 



of No. 24 double cotton covered wire. Ex- 
perimenters who desire to wind their oscilla- 
tor coils, and are unable to make cross-wound 
coils, can use Lorenz (basket-weave) such 
as made by the Perfection Coil Co. or Sickles 
(diamond-weave) coils, and attain the same 
results, although the coils should be set back 
some distance from the oscillator variable 
condenser. By a cut-and-try method, the 
right number of turns can be ascertained, 
the calibration being determined by changing 
the old receiving set to 600 meters (or as high 
as possible), and adjusting turns on the oscil- 
lator grid coil until 545 meters comes in at 
approximately 95 on the oscillator dial, and 
220 meters at 5 on the dial. Without fixed 



of coupling that is good for some frequencies 
and poor for others. 

The best value of coupling for a given 
frequency is minimum coupling; in other 
words, the coupling should be decreased until 
the point is reached where the tube is just 
ready to stop oscillating. By finding this 
coupling distance for all frequencies, a point 
can be determined that will give the best 
average coupling for all frequencies. In the 




RADIO BROADCAST Photograph 



FIG. I I 



End view showing the method of placing the condenser some distance behind the panel to 
lessen body capacity effects. The separation of the coupling coils is clearly shown here 



condenser G of Fig. 4 it would be impossible 
to obtain this spread on the dial and the 
capacity of this condenser will have to be 
determined by trial. The value used in the 
frequency-changer shown in the photograph 
was .00013 m fd. 

As mentioned above, in the usual oscillator 
coupler the coupling between plate and grid 
coils is fixed. Yet the best value of coupling 
varies with the frequency, and experiments 
have shown that most couplers have a value 



coupler shown in Fig. 10 this point is deter- 
mined by test, and the coil locked in place. 

HOW TO PUT THE " SUPER*' TOGETHER 

MOUNT all apparatus on panel and base- 
board, assemble the oscillator coupler 
on rear of .00025 m ^. condenser, or some 
distance back of the condenser if other than 
cross-wound coils are used. Connect the 
parts as per connection diagram Fig. 10, 
soldering wires to the terminal lugs instead of 



262 



Radio Broadcast 




RADIO BROADCAST Photograph 



FIG. 12 



A perspective of the completed frequency changer. The grid leak 
and condenser are supported by the tube socket and the wiring to it 



wrapping them around screws. Connections 
to Si and 82 on the pickle-bottle coil should 
preferably be of flexible wire, as these two wires 
must be disconnected if a loop is to be used. 
A loop can be used when this unit is to be at- 
tached to a multi-tube set such as a neu- 
trodyne, or tuned radio frequency set. If 
the unit is to be used with a single-circuit or 
three-circuit regenerative set, a loop can be 
used if maximum selectivity and a range of 
100 to 200 miles is all that is desired. 

After all internal connections are made, 
connect the battery terminals to the same 
battery terminals on your present set, making 
sure that positive B on the frequency-changer 
has a value of at least 45 volts. You will 
notice that there is no minus B on the 
frequency-changer. This is because this 
connection is taken care of in your present 
set. Connect the antenna and ground to 
the frequency-changer instead of to your 
present set. If you have a five- or six-tube 
radio frequency set, you may use a loop in- 
stead of the antenna and ground by dis- 
connecting Si and S2 of Fig. 2 from the 
secondary windingof the pickle-bottle coupler. 
Now tune your receiving set to 600 meters, 
get maximum regeneration, and leave your 
dials set. All tuning is now taken care of by 



the two dials on the frequency-changer panel 
and regeneration can be obtained by rotating 
the pickle bottle tickler. 

CARE MUST BE USED IN CONNECTIONS 

BE VERY careful to examine the circuit 
in your set to which the output circuit 
of the frequency-changer is connected. This 
circuit must not be connected to the A battery 
circuit, or else there will be a short-circuit 
across 45 volts of the B battery. In some 
regenerative sets, and in neutrodynes, the A 
battery is grounded and this connection 
must be broken. 

In an article to follow we will show a num- 
ber of single-tube regenerative circuits and 
discuss the connections to, and operation of, 
the frequency-changer. We will also show 
how it is possible to "tune-in by the squeal" 
without annoying your neighbors. We will 
show the frequency-changer connected to 
a neutrodyne circuit and illustrate how to 
operate it on an antenna or on a loop. Best of 
all will be a method of connecting a 
frequency-changer to a crystal set, giving the 
long distance range of a single tube set with 
the selectivity equal to the finest super- 
heterodyne circuit. This makes a one tube 
circuit with the finest selectivity known. 



Phonograph 
Receiver 



Radio 



Broadcast s 



An Entirely New Method of Building the 
Four-Tube Knock-out Receiver to Fit in 
Any Phonograph A Design Which Sets 
A New Mark for Home-Built Receivers 



By ARTHUR H. LYNCH 




THE most popular phonograph to-day 
is the phonograph in which radio is an 
integral part. It is possible to double 
the use and value of the many 
thousands of phonographs in this country 
to make them better instruments for the home 
by using some sort of radio receiver in connec- 
tion with them. For some months, it has been 
possible to buy factory-made radio receivers 
which could be fitted into a compartment of 
the phonograph. But the home constructor 
has had to worry along as best he could. 

RADIO BROADCAST has determined to ex- 
periment with the idea of furnishing the best 
design possible for home constructed receivers 
in the phonograph. We are gambling on 
our conviction that the home constructor, that 
everyone, in fact, is interested in making the 
phonograph a more valuable bit of domestic 
equipment. To that end, we have spent a 
great deal of time and money in canvassing the 
entire situation and we shall bring to you every 
month, for some time to come, the results of 
our findings. Those findings, we think, involve 
some distinctly new ideas in radio construction. 
We shall offer you an opportunity to build 



various models of one of the most compact and 
efficient radio receivers for home construction 
that we have ever seen. 

The phonograph is a very satisfactory means 
of entertainment, and we feel sure that by 
the proper design of a receiver for incorpora- 
tion in practically any model of phonograph 
we are going to present something of great 
use to a large number of people. Many a 
perfectly good phonograph has been done out 
of a home by the radio set. Many more have 
been pushed aside, and their sole present use 
is to hold a beautiful lamp or a flower pot. 

HOW TO GET THE MOST RADIO IN THE LEAST 
SPACE 

RADIO has brought a new problem into the 
home. Space in many modern homes is 
often scarce. When the piano, the books, the 
library table, and the phonograph are prop- 
erly placed, where to put the radio receiver 
has caused many brows to wrinkle. If 
a phonograph is part of the household equip- 
ment, it is often necessary to relegate it to an 
inconspicuous corner. And, if our observa- 
tion counts for anything, there are entirely 



264 



Radio Broadcast 



too many phonographs that are now gathering 
whatever dust the housewife will permit it to 
collect. Too many phonographs are not used 



from one end of the year to the other. This 
has been the case in the homes of a number of 
our staff and in the homes of many people 
with whom we come in contact. We hope 
to show the home constructor how he may very 
desirably combine the beauty of his phono- 
graph with the efficiency and compactness of a 
home constructed four-tube receiver. 

Home constructors, ever since they began 
their researches with blue print and pliers 
have naturally turned more of their attention 
to the electrical side of their receiver than 
they have to what might be called the aesthe- 




RADIO BROADCAST 

Photograph 

FIG. I. A SIDE VIEW OF MODEL NO. I 

The principal points shown in this illustration are the extreme rigidity of 
assembly and indication of the compactness of the unit. In this case a panel 
fourteen inches high has been used to fit the console requiring a vertical as- 
sembly. In an assembly of this kind it is entirely practical to fit it into a 
wooden carrying case for camping purposes. Dry cells and the necessary B 
batteries may have plenty of room below the receiver assembly. Though 
dry cell tubes may be used in this way better results are obtained from stan- 
dard tubes and the use of the Lynch lead is very useful for camping purposes 
as illustrated on pages 252-3. The use of a small switch mounted in the an- 
tenna coupler to permit regulation of the left hand tuning dial for antennas 
of different lengths makes the panel assembly more presentable Since this 
switch need only be adjusted once for a given antenna and then remains a 
fixture there is no need for having it on the panel. Manufacturers assure 
us that they will soon market switches and fittings for this purpose. This 
idea was suggested to us by P. R. Morrison of Freeport, Long Island 



Radio Broadcast's Phonograph Receiver 



265 




FIG. 2. 



RADIO BROADCAST Photograph 
TOP VIEW OF THE PHONOGRAPH UNIT 



Particular attention is called to the assembly of the sub-panel as well as the position of the tube sockets. In 
order to permit the complete unit to be used in either a vertical or horizontal position without requiring a 
single change in construction and to offset the possibility of the tube filaments sagging and touching the grids, 
the correct placing of the sockets is important. Manufacturers who are to market a four-tube sub-base of 
this type at our suggestion have agreed to see that tneir products incorporate this attractive and important 
feature. Even though this receiver is very compact it will be observed that there is no crowding 



REAR VIEW OF RADIO BROADCAST S 
COMBINATION CONSOLE 



By placing the receiver assembly well toward the top of the panel 
plenty of room is found for locating all the batteries below and be- 
hind the radio panel. The back of the phonograph has been re- 
moved to show the location of the various units 




2 66 



Radio Broadcast 




FIG. 4 

A loud speaker and phonograph 
tone-arm now available commercially 



tic side. If the set was put together and it 
worked, the cabinet in which the set was con- 
tained was often a secondary consideration. 

RADIO BROADCAST'S Phonograph Receivers 
will allow the constructor to utilize the hand- 
some qualities of his phonograph cabinet, and 
the excellent sound chamber of that instru- 
ment. For these two reasons alone, we be- 
lieve that many, many phonographs are going 
to come out of the shadow, not only to be 
seen but to be used again. 




FIG. 6. FROM THE REAR 
This is how the unit appears 



RADIO BROADCAST Photograph 



Radio Broadcast's Phonograph Receiver 



267 



FIG. 6A. AN- 
OTHER REAR 

VIEW 

Showing how other 
coils and condensers 
may be employed 
without any change 
in layout 




RADIO BROADCAST Photograph 




RADIO BROADCAST Photograph 
FIG. 7. FROM THE BOTTOM 

We get some idea of the wiring. In this unit we have used audio transformers of rather large physical 
dimensions in order to be sure that practically any transformers may be used without undue crowding. 
Amperites are used in the filament circuits of the push-pull tubes to reduce the number of manual controls 
as in Fig. 12. In receivers designed for use with UV-IQQ or similar tubes for operation from flashlight or dry 
batteries it is sometimes advisable to use a single rheostat for the two tubes as shown diagrammatically 

in Fig. 1 1 



268 



Radio Broadcast 




FIG. 8. ANOTHER SAMPLE 



RADIO BROADCAST Photograph 



In this arrangement another group of audio transformers are used and the spring sockets have been replaced 
by the rigid type. In order to cushion the tubes two strips of sponge rubber are placed between the sub- 
panel and its supporting brackets. In this receiver, flexible wiring is used and a series of wires with special 
colored covering as described in the article on standardization in the April RADIO BROADCAST is suggested. 
It is not a difficult matter to arrange color combinations within the receiver just as standards have been 
suggested for the wiring outside the receiver. It is not unlikely that design of this nature will soon find its 
way into receivers other than those for home construction. Wire manufacturers assure us they will soon be 
ready to supply such wire. It is well to compare this unit with Fig. 6. There was no noticeable difference 
in performance. Convenience for your particular assembly problem is the factor to decide upon between 

the two 



If you use this combined radio-phonograph 
unit, there is no reason why you should ever 
be deprived of the very best in the world's 
entertainment. When the radio programs 
do not suit your mood, there is certain to be a 
record among your collection which will suit 
the occasion. The radio receiver and the 
phonograph have taken a tremendously im- 
portant place in the home, and RADIO BROAD- 
CAST believes that both should be used to their 
fullest capabilities. 

A radio receiver for a phonograph has to 
be designed so that it will fit the various cabi- 
nets in which it might be installed. The 
RADIO BROADCAST Phonograph Receiver con- 
sists of an extremely compact unit employing 
the excellent circuit developed for us by Walter 
Van Braam Roberts of Princeton University. 
The unit itself is so designed that it can be 



adapted to a panel of any size. The dimen- 
sions of the panel conform to the size of the 
phonograph cabinet into which the receiver is 
to be put. 

THE MAIN FEATURES OF THE PHONOGRAPH 
RECEIVER 

COLLOWING articles will show just how 
* to build this receiver, down to the 
very last binding post and drop of solder. 
The photographs which are reproduced with 
this story show just what we have been able 
to do with the Phonograph Receiver and 
several representative types of phonograph 
cabinets. For the experienced radio construc- 
tor, the photographs are self explanatory, but 
for the builder who sets great store by com- 
plete constructional details and diagrams, the 
later articles will show exactly how it is done. 



Radio Broadcast's Phonograph Receiver 



269 



The main feature of the Phonograph Re- 
ceiver is its wonderful compactness. The panel 
layout, as you will observe, is extremely sym- 




FIG. 9. A SIMPLE METHOD OF CONVERT- 
ING THE TONE CHAMBER OF A PHONOGRAPH 
INTO A LOUD SPEAKER 



metrical. The assembly of the parts is not 
particularly difficult and the results which 
we have obtained with several models with 
which we have been experimenting have been 
highly satisfactory. This Phonograph Re- 
ceiver combines all the good features of 
the Four-Tube Knockout, plus some very 
significant mechanical and electrical improve- 
ments.' By referring to the announcement 
of the Better Receiver Contest, which appears 
on another page of this magazine, you will 
find listed the qualifications which the Roberts 
Knockout receiver possesses. We believe 
that tube for tube, dollar for dollar, and result 
for result, this is by far the best receiver ever 
designed for home construction. 

After we had satisfied ourselves that we 
had the best possible receiver for the purpose, 
the next most important point was the actual 
mechanical layout of the parts. In this, we 
feel, we have been highly successful. 




RADIO BROADCAST Photograph 
FIG. IO. THE UNIT ON A SMALLER PANEL 

This model was made to illustrate the points outlined in Fig. 8 and shows a very symmetrical panel design. 
The application of a unit like this to any phonograph is a very simple matter. It is merely necessary to pro- 
cure a piece of five ply veneer large enough to fill the desired space, cut a hole in wherever the unit will fit 
most satisfactorily and set it in place. If, to conserve space, it is necessary to install the receiver in a side- 
wise position, the precaution concerning the position of the tube sockets to prevent sagging filaments touch- 
ing the grids must be taken into consideration and the mounting of the sockets changed accordingly. The en- 
graving may then be put on the proper part of the panel to make reading the dials from the side unnecessary 



270 



Radio Broadcast 



,OU1S1DE LtfcO 


I 7 


<i- ^ 


2 


'PIKTES 


IV. = 



iiCj T * T 

~IH " s "oKJ- 




FIGS. 11-12. THE SIMPLEST WIRING ARRANGEMENT 

Is shown in Fig. 1 1 . It differs from Fig. 12, (below), in several minor details. Simple jacks are used instead of 
those incorporating the filament control feature. A rheostat controls the filaments in the push-pull tubes in- 
stead of the Amperites. This circuit is a much simpler wiring job but where the receiver is to be used by the 
entire family the additional wiring necessitated by Fig. 12 will be found very much worth while. The dotted 
lines in both these diagrams illustrate simple and effective methods for overcoming any difficulties which 
may arise in the audio amplifiers such as a continual whistle which was observed when certain transformer 

combinations were used 




FIG. 12 



The possibilities of this Phonograph Re- 
ceiver are best shown by an examination of 
the accompanying illustrations. 

A great many Victor phonographs of the 
upright type are in use to-day. In these, the 
record cabinet is of two kinds. Some have 
two sets of shelves; the upper holding books 
for ten-inch records and the lower holding 
books for twelve-inch records. In order 
to fit the Phonograph Receiver in such a 
cabinet, it is merely necessary to remove the 
upper shelf and find some other convenient 
place for them. An unused corner of a book- 
case does very well. A panel of wood or some 
composition is then made to fit the space 
previously occupied by the record-books and 
the receiver-unit is then fitted directly to this 
panel, or to a sub-panel mounted on the 
panel which is substituted for the record- 
book shelf. 

The illustrations show that this radio- 
phonograph combination will save a great 
deal of space, and since the storage battery and 
the B batteries may be included in the phono- 
graph itself they are permanently placed out of 
sight. This is, of course, impossible when the 
radio set is used on some sort of table 



In another upright Victor model, there are a 
series of four to six shelves used to hold the 
phonograph records, with books to contain 
them. In placing the Phonograph Receiver 
in such a cabinet, it is only necessary to 
measure about twelve inches down from the 
upper end of the record space, remove the 
shelves and have a panel of wood or composi- 
tion made to fit this space. 

There are a great many receiver devices 
now on the market which enable one to use a 
so-called loud speaker attachment with the 
phonograph. These devices are connected to 
the audio output of the receiver and the unit 
itself mechanically coupled to the tone-arm of 
the phonograph. The sound compartment of 
the phonograph is used as the loud speaker. 
This operation is very simple, as can be seen 
from one of the illustrations. The character 
of the signal resulting from the use of a good 
loud speaker attachment and the phonograph 
itself as the "loud speaker" is extremely good. 
There are also some new types of tone-arms 
which combine both the tone arm for the 
phonograph and an attachment for employing 
the loud speaker unit. In such a combination, 
the phonograph or loud speaker attachment 



Radio Broadcast's Phonograph Receiver 



271 




FIG. 13. ANOTHER SUB-PANEL (BOTTOM VIEW) 

All the wiring shown in this illustration may be done before the sub-panel and main 

panel are permanently joined. In order to conserve space the strip carrying the binding 

posts is held away from the outer end of the brackets by two bushings and long machine 

screws. The space saved in this way is nearly f of an inch. Units like this completely wired are soon to be 

placed on the market. The Radio Research Laboratories, New York City, are the originators of this unit 

idea. It would be well to compare this illustration with Fig. 7 to note the changes 



may be used at will without taking the sound 
box from the tone arm. A tone-arm of the 
sort described has been used in our laboratory 
and has produced very satisfactory results. 
In our experiments with this new design, we 
have used a great number of different radio 
parts designed for the same purpose. In prac- 
tically every case, the overall efficiency of the 
resulting models has been substantially the 
same. For example, we have used a number 
of different types of transformers. We have 
used various kinds of coils, various makes of 
rheostats, and vacuum tube sockets. We 
have not as yet been able to use standard 
jacks in this receiver, although we are working 
on that problem now. It may, perhaps, be 
difficult for some of our readers to secure cir- 
cular jacks as used in these Phonograph Re- 
ceivers in their locality, but these may be 



obtained by mail order in a few days from al- 
most any part of the country. 

What we are trying to do is to present a 
design, which in the final analysis will give 
satisfaction, even in the hands of an inex- 
perienced person. We are trying to make it 
possible for the home constructor to obtain 
the necessary parts without putting himself to 
a great deal of trouble. By incorporating 
as we have, well known, standard parts, we 
have made it possible for the radio dealer to 
supply all the necessary units for this receiver 
with a minimum of trouble. 

All those who have seen the first models of 
the RADIO BROADCAST Phonograph Receiver 
are unanimous in agreeing with us that it fills 
a distinct need of the home constructor. The 
next article will describe the building of this 
receiver. 



MARCONI HIMSELF 



I I AS written about his most recent experiments. During late years, 

^ Senator Marconi has centered his energies on perfecting a method 

for transmitting guided radio waves and he believes that one of the great 

developments is in radio "beam" transmitting. Senator Marconi's article 

will appear exclusively in RADIO BROADCAST for July. It contains many 

interesting photographs never before published in this country. 



QUESTIONS AND ANSWERS 
\j? 




See Important Special Announcement on Page 278 
QUERIES ANSWERED 



WHAT is THE FUNCTION OF A DETECTOR TUBE? 
A. G. N. Atlanta, Ga. 

WlLL YOU PUBLISH A CIRCUIT ON IMPEDANCE 
COUPLED AUDIO-FREQUENCY AMPLIFICATION? 

L. P. San Antonio, Tex. 



WHAT is THE CIRCUIT DIAGRAM FOR INCLUDING A 

I IO-VOLT LAMP IN A B BATTERY CIRCUIT FOR 
PROTECTING THE TUBE FILAMENT? 

P. V. O. Grand Rapids, Michigan. 



WHAT is THE PROPER WAY TO STAIN AND POLISH 

A HOME-MADE CABINET? 

N. D. Nashville, Tennessee. 

EXPLAIN IN DETAIL THE USE OF THE COIL WINDING 
CHART FOR DETERMINING CONDENSER CAPACITY, 
J. H. W St. Louis, Mo. 

WERE THE DIMENSIONS USED FOR THE PANEL IN 
THE CONSTRUCTION OF THE TWO-STAGE RADIO- 
FREQUENCY AMPLIFIER IN THE MAY, 1925, ISSUE OF 
R/.DIO BROADCAST CORRECT? 

L. G. Chicago, 111. 



HOW A DETECTOR TUBE DETECTS 

THE term detect is somewhat erroneous when 
used in describing the function of a vacuum 
tube detector. If our ear mechanisms were 
able to respond to radio signals as they are trans- 
mitted, there would be no need for detector tubes. 

However, the frequency, or in other words, the 
rapidity with which the radio vibrations are pro- 
duced, is too great for us to hear, so that some means 
of reducing the number of vibrations must be em- 
ployed. The action is one of rectification rather 





Filament 



FIG. I 



FIG. 2 



than one of detection. For instance, the maximum 
number of vibrations that can be heard by the 
human ear is about 20,000 cycles, while the mini- 
mum number that can be heard is but 16 cycles. 



RADIO BROADCAST ADVERTISER 



273 





Do you know 

where Condenser losses 

Come, -from? 

TDESISTANCE LOSSES are 

the losses which most serious- 
ly affect the efficiency of aconden- 
ser when at working "radio ^ fre- 
quencies. They arise from poor 
contacts between plates and from 
poor bearing contacts.. Soldered 
plates and positive contact spring 
bearings reduce these losses to .a 
minimum. N 

Eddy current fosses occur 'in 
metal end plates and the conden- 
ser plates themselves. While not 
so serious as resistance losses, 
they increase with the frequency, 
and therefore should be kept as 
low as possible. 

Dielectric losses are due to ab- 
sorption of energy by the insulat- 
ing material. Inasmuch as they 
vary inversely as the frequency, 
they have less effect upon the 
efficiency of a condenser at radio 
frequencies than any other set of 
losses. The use of metal end 
plates in short-wave reception to 
eliminate dielectric losses is never 
justified, because they introduce 
greater losses than well-designed 
end plates of good dielectric. 



The design of General Radio Condensers 
is based on scientific facts and principles, 
not on style and fancies. 

Specially shaped plates always in perfect 
alignment give the uniform wave-length 
variation which, permits extremely sharp 
tuning.? 

Rotor plates are counterbalanced to make 
possible accurate dial settings. 

In 1915 the General Radio Company in- 
troduced to this country the first Low Loss 
Condenser, and . ever . since has beenjthe 
leader in condenser design. 

Lower Losses and^Lower Prices make 
General Radio Condenserslthe outstanding 
values of condenser design. 

Licensed for multiple tuning under Hogan 
Patent No. I t 014,002 

Type 247-H, with geared Vernier 
Capacity, 500 MMF. Price 

Type 247-F, without Vernier </> 
Capacity, 500 MMF. Price ^J 

GENERAL RADIO CO, 

. A CAMBRIDGE, MASS. 




Quality Parts 



Tested and approved by RADIO BROADCAST 



274 



Radio Broadcast 



Now waves of greater or lesser frequencies than this 
must be either increased or reduced before they can 
be heard. To accomplish this purpose, a detector, 
or rectifier, is used, which breaks up the frequency 
of the oscillations into groups and makes it possible 
to hear the vibrations as they are recorded on the 
telephone diaphragm. 

The elements of which the tube consists are (A) 
a filament which is energized by a source of direct 
current (storage A battery.) Around this filament 
is (B) a wire mesh or grid. Then outside and around 
the grid is (C) a metallic member termed the plate. 
These elements are supported by wire rods imbedded 
in a glass tube from which the air has been evacu- 
ated. Convenient contacts are provided by prongs 
protruding through the base. 

Diagrammatically, the vacuum tube is repre- 
sented as in Fig. i while Fig. 2 shows a vacuum tube 
connected in an ordinary receiving circuit. 

The action of the circuit and the function of the 
tube are as follows: 

The antenna circuit consisting of the antenna, pri- 
mary, the variable condenser and the ground, have 
been adjusted to the wavelength of a transmitting 
station. 

The secondary circuit, S-C 2 , to which is connected 
the vacuum tube, its batteries and phones, is tuned 
in resonance with the primary. 

This makes it possible to receive energy in the 
antenna circuit so as to set up an electro-magnetic 




CONSTANT AMPLITUDE ALTERNATIONS 



FIG. 3 



Rl 

na 



field, which induces a voltage in the secondary cir- 
cuit. 

Now, by referring to Fig. 2, it will be seen that 
there are, primarily, three parts to the circuit. 

When the filament is lighted to incandescence it 
emits electrons which flow to the plate, so that when 
a signal is received, it sets up in the antenna circuit 
an electro-magnetic field, due to the variations in 
amplitude of the received signal. See Fig. 
3A and B. This field induces in the secon- 
dary, or grid circuit, a voltage which 
charges the grid condenser. 

Doctor Van der Bijl explains the suc- 
ceeding rectifying action as follows: 

"When the grid potential becomes 
positive, electrons are attracted to 
the grid and during the next half cycle 
when the grid potential becomes 
negative, the electrons cannot escape 
from the grid, because they are 
trapped on the insulated part of the 
circuit comprising the grid and the one 
plate of the condenser C3- During the 
next positive loop of the incoming 



wave the grid attracts more electrons, which 
are also trapped so that they cannot escape 
from the grid during the succeeding negative 
loop. In this way, the grid builds up a nega- 
tive potential, and the high frequency poten- 
tial variations on the grid, vary around a mean 
value of the grid potential, which becomes more 
and more negative as the strength of the in- 
coming oscillations increase. This reduces the 



Grid potential 





Audio current 
in telephone 



FIG. 4 

plate current, and if the condenser C3, and the 
insulation of the part of the circuit comprising 
C3 and the grid were perfect the plate current 
would be permanently reduced and this would 
make the tube inoperative. To prevent this, 
a high resistance leak, R2, is shunted across 
the condenser, its value being so proportioned 
that the electrons cannot leak off this resis- 
tance to any appreciable extent in a time com- 
parable with the period of the high frequency 
oscillations. But the electrons do leak off in 
the time of the order of magnitude of the low 
frequency variations of the amplitude of the 
high frequency oscillations. The result is, 
that the potential of the grid takes such values 
as are represented by the curve in Fig. 4A. 
The high frequency variations in the plate 
circuit pass through the condenser C4 inserted 
in the output circuit, and the current in the 
telephone receiver takes the shape shown by 
the curve in Fig. 48." 

The current passing through the phones ener- 
gizes the electromagnets and conforms with its 

Isolating condensers 

2mfd./ 1st Audio '. 2 T. fd - 2nd Audio 

Amplifier 




9 A 



FIG. 



RADIO BROADCAST ADVERTISER 



275 





positive as BjgBen 



SET Big Ben at seven and at seven o'clock you're bound to 
get the alarm. 

Just so, the Ultra-Lowloss condenser can be set at any wave- 
length the corresponding station will come in clear and sharp. 
You know instantly where to turn, once a station of known 
wavelength is located. Makes tuning easy direct positive. 
Special Cutlass Stator Plates spread wavelengths evenly over 
a 100 degree scale dial so that each degree represents approxi- 
mately 3J meters. 

Ultra-Lowloss condensers are designed by R. E. Lacault, 
originator of the famous Ultradyne Receivers, and built upon 
scientific principles which overcome losses usually experienced 
in other condensers. 

At your dealers, otherwise send purchase price and you will be 
supplied postpaid. 

Design of lowloss coils furnished free with each condenser for 
amateur and broadcast wavelengths showing which will function 
most efficiently with the condenser. 

J. Q Manu f acturer8 who Wish To Improve Their Sets 

Mr. Lacault will gladly consult with any manufacturer regarding the appli- 
cation of this condenser to his circuit for obtaining best possible efficiency. 



TUN.NS CONTROL 

Simplifies radio tuning. Pencil- 
record a station on the dial there- 
after, simply turn the finder to your 
pencil mark to get that station in- 
stantly. Easy-quick to mount. 
Eliminates fumbling, guessing. Fur- 
mshed clockwise or anti-clockwise 
in gold or silver finish. Gear ratio 
20 to 1. 

Silver, $2.50 Gold, $3.50 

PHENIX RADIO CORPORATION - 116-C East 25th Street - New York 





. l 



CON DENSER 



Tested and approved by RADIO BROADCAST 



276 



The Grid 



strength, actuating the diaphragm which produces 
sound vibrations which are audible to the ear. 

IMPEDANCE-COUPLED AUDIO AMPLIFICATION 

FOR those who wish to experiment with choke 
coil audio amplification, the circuit in Fig. 5 
is especially interesting. 

A detector and two-stage amplifier is shown. 

In the plate circuit of the detector and first stage 
amplifier, the variations in voltage drop take place 
in the choke coils. These variations are impressed 
on the grid of the succeeding tube through the large 
isolating condenser. In the amplifiers the grid 
leaks connected from the grids to the negative side 
of the filament (through a small C battery) furnish 
a path for excessive negative voltages, which are 
accumulated on the grid, to leak off. 

The choke coil may be the secondary of an audio 
transformer. Usually transformers having burned 
out primaries may be found in the junk box of the 
radio laboratory which will fit in nicely here. 

The small C battery applies a negative bias on the 
grids which permits the amplifier tubes to operate 
on the proper point on their characteristic curve. 

The value of an isolating condenser is such that a 
minimum of voltage loss is effected by its use. 

Besides being a coupling agent between the plate 
and grid of adjacent tubes, this condenser isolates 
the high B voltage from the grid of the tube. 

The values of the parts are Ci .00025 rnfd., C.2 
2 mfd.; C3 2 mfd.; C^ .001 mfd: Ri 3 megohms; 
R2 and R3 ^ to 2 megohms. 



THE LAMP AS APPLIED TO A STANDARD CIRCUIT 

m 



J&. 

R 




- B 



Safety Lamp 



25 or 50 Watt Tungsten 
Filament Lamp inserted in 
/ the-B lead 



I I I I I I I I 

B Battery 
FIG. 6 



A TUBE PROTECTOR 

VERY often radio tubes are consigned to the 
junk heap because some too enthusiastic 
experimenter was not careful enough to keep 
his high voltage B battery leads away from the 
filament circuit of his receiver. 

By the simple addition of a 25 or 50 watt lamp 
inserted in the negative B battery lead (Fig. 6), 



tubes may forever be protected from blow-outs. 
Ordinarily the negative side of the B battery con- 
nects to either the plus or minus of the A battery. 

Assuming that the connection is made to the plus 
A, if the plus B should happen to come in contact 
with the minus A, then 45 or 90 volts (as the case 
may be) would be applied to 6 volt filaments. 
Result: blown out tubes. 

Now, by placing the lamp in the negative side of 
the B battery, the full voltage of the battery is 
applied to its filament thereby choking off the B cur- 
rent and so protecting the tube filaments due to the 
relatively high resistance of the lamp being inserted 
in series in the circuit. The tungsten type of lamp 
seems to give better results than the carbon filament 
type. Ordinarily if the plus B lead should touch the 
plus A lead then the B battery would become short- 
circuited, but if the lamp is in the circuit it will 
indicate the connection by lighting brilliantly. 

STAINING AND POLISHING CABINETS 

THE true constructor must know a bit about 
the carpentry that enters into the make-up 
of a receiver. The art of carpentry is closely 
allied with the radio art as is manifest in the elabo- 
rate cabinet designs now so plentiful in the radio 
market. 

For the home-constructor, a few pointers on 
staining and polishing will not be amiss. There 
are several kinds of stains, namely, the, alcohol 
stain, the penetrating stain, and the oil stain. The 
first two named seem to act better for quality 
work, although no doubt good work may be accom- 
plished with oil stain. This discussion will apply 
only to the penetrating and alcohol stains. 
The equipment needed is as follows: 

1. A small supply of alcohol one pint. 

2. Stain. 

3. Cheesecloth pad made with cotton waste. 

4. Steel wool. 

5. Rotten stone. 

6. Wax (in powdered or grease form). 

7. Shellac one-half pint jar. 

The cabinet is first coated evenly with the stain 
until the desired shade is obtained. Shellac is 
applied with the cloth pad so that the entire surface 
is covered. Then with the alcohol, the surface is 
lightly washed, which removes much of the surplus 
shellac. After this coat is allowed to dry for about 
twenty minutes, another coating of shellac is applied 
which is again washed down with the alcohol. This 
is repeated until the desired surface effect is ob- 
tained. Then, with rotten stone the surface is fully 
cleaned, after which it is rubbed down by the steel 
wool. Finishing touches consist of polishing with a 
waxed cloth. 

THE COIL WINDING CHART FOR CALCULATING CA- 
PACITY 

IN LAST months' RADIO BROADCAST, a chart 
for the computation of coil sizes was described 
on page 46, which would aid the experimenter 
in determining the proper size coil required where 



RADIO BROADCAST ADVERTISER 



277 



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WGR Buffalo 
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THE long-lasting power of Evereadys 
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false economy to buy batteries that may 
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and size, Evereadys are the most 
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Buy Eveready "B" Batteries. To light 
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2jS Radio Broadcast 

a certain sized condenser was designated to tune is indicated by where this last line touches the in- 

:i circuit to a predetermined wavelength range. ductance scale, and by knowing the maximum 

In the article it was mentioned that the chart wavelength range desired, we draw a line between 

might be used in the reverse manner, where the-coil these two points and continue the line on to the 

size and wavelength range desired were known, to capacity scale. This intersection at the capacity 

determine the value of variable condenser needed to scale gives us the maximum capacity of the variable 

accomplish this end. condenser necessary for tuning the coil in question 

In detail this reverse operation is described as to the maximum wavelength indicated, 
follows: 

Count the number of turns per inch on the coil CORRECTED DIMENSIONS 
and measure its length. On the chart connect 

these two points by a pencil line. Then determine A I ^HE dimensions for the panel used in the con- 

the diameter of the coil and at that value on the struction of the two-stage radio-frequency 

chart and draw a line to intersect with the one 1 amplifier described in the May, 1925, issue of 

previously drawn, at the index line and at the indue- Radio Broadcast Magazine should read as follows: 

tance scale. Panel 7 inches wide, 18 inches long, and f\ inch 

Then by knowing the inductance value, since it thick. 



Before Ton Write to the Grid 

THOUSANDS of you are writing the Grid for technical advice every month. The 
expense of framing a complete and exhaustive reply to each letter is very high. The edi' 
tors have decided that the benefit of the questions and answers service will continue to be 
extended to regular subscribers, but that non'subscribers, from April 15, on, will be charged 
a fee of $1 for each letter of inquiry which they send to our technical department. Very 
frequently, our technical information service proves of definite money value to you who 
write us, for we are often able by a sentence or two of explanation, to put you on the right 
path before you have made a perhaps expensive mistake. 

The occasional reader of RADIO BROADCAST will be charged a fee of $1 for complete 
reply to his questions, and the regular subscriber can continue to take advantage of the 
service as before. In that way the non-subscriber will help share the cost of the technical 
staff whose service he gets. Every letter receives the benefit of the experience of the editor 
and the technical staff and every correspondent may be sure that his questions will receive 
careful consideration and reply. 

When writing to the Grid, please use the blank printed below. 



GRID INQUIRY BLANK 

Editor, The Grid, 

RADIO BROADCAST, 

Garden City, A[eu> Tor\. 
Dear Sir: 

Attached please find a sheet containing questions upon which \indly give me fullest 
possible information. I enclose a stamped return envelope. 

(Chec\ the proper square) 

CD I am a subscriber to RADIO BROADCAST. Information is to be supplied to me free 
of charge. 

CD I am not a subscriber. I enclose $1 to cover costs of a letter answering my questions. 

My name is- 

My address is 



RADIO BROADCAST ADVERTISER 



279 




By-Pass 



noises and 





Y-PASS Condensers do a double 
job. They filter the fluctuating 
"B" battery current. They provide a 
free path for the radio frequency cur- 
rents around the high internal resis- 
tance "B" battery. 

The first function tends to remove 
disturbing noises the second increases 
efficiency by reducing losses and prop- 
erly routing the available energy. 

The tone quality of every set will be 
greater in strength purer smoother 
with a By-Pass Condenser. 



External connections for the By- 
Pass Condenser may be made by 
connecting it from the minus "B" 
terminal to the plus "B". 




Dubilicr 

CONDENSER AND RADIO CORPORATION 



Tested and approved by RADIO BROADCAST 



New Equipment 




SEE-ESS WINDER 

The winding of numerous inductances for ex- 
perimental work is made easy with the above 
apparatus. The result is a self-supporting 
diamond weave coil of any desired inductance. 
A desirable addition to the constructor's labor- 
atory. Distributed by the Wireless Electric 
Co., 204-206 Stanwix St., Pittsburgh, Pennsyl- 
vania. Price, $10.00 




KELLOGG REPRODUCER 

The unit of this speaker is of special 
construction, having a magnetically 
modulated diaphragm. Coupled 
with this is the horn which was de- 
veloped to be as nearly correct 
acoustically, both as to shape and 
material, as possible. This repro- 
ducer covers practically the entire 
auditory range of sound waves very 
successfully. Made by the Kellogg 
Switchboard & Supply Co., Adams 
& Aberdeen Sts., Chicago, Illinois. 
Price, $20.00 



BALLGRIP 

BINDING 

POST 

These interesting 
binding posts re- 
present a new 
idea in this field. 
Connections may 
be made instantly 
and the opening 
in the post is 
large enough for 
receiver cord tips. 
Springs force the 
ball to make good 
electrical contact 
when a wire is 
placed in position. 
The fact that 
there is no head 
to loosen and be 
lost is a decided 
point in its favor. 
Made by the 
Quality Moulded 
Products Inc., 
Jersey City, New 
Jersey 




BELDEN LOOP WIRE 

A wire composed of 60 strands of bare copper 
twisted with 5 strands of half hard phosphor 
bronze wire. This twist is then covered with 
cotton and finally with a good looking brown 
covering to match the better grades of loop 
frames. Made by the well known makers of 
wire, the Belden Manufacturing Company, 
Chicago, Illinois 




VELVET VERNIER DIAL 

An all-vernier dial with a ratio of approximately 
four to one and is entirely free from back -lash. 
With this dial you not only enhance the appear- 
ance of your receiver but also make tuning very 
easy. Made by the National Company, Inc., 
110 Brookline St., Cambridge, Massachusetts 



RADIO BROADCAST ADVERTISER 



321 




WD-11 

WD-12 
UV-199 

UV-200 
UV-201-a 

Radiotrons with these model 
numbers are only genuine when 
they bear the name Radiotron 
and the RCA mark. 



* 



in Names 



Do you buy things by name because the name 
tells the quality? Do you ask for a RADIOTRON, 
instead of just a "vacuum tube" demand the 
standard by the name that marks it as genuine? 

The most important part of a radio set is the tube, 
and you can't get the best out of any set without 
putting the best tubes into it. There's a Radio- 
tron for every use, in every kind of set. Look 
for the name and the RCA mark and be sure 
it is genuine. 

Radio Corporation of America 

Sales Offices: Suite 37 

233 Broadway, New York 10 So. La Salle St., Chicago, 11L 

28 Geary Street. San Francisco, Cal. 




Radiotr 



REG. U.S. PAT. OFF. 



PRODUCED ONLY BY RCA 




Tested and approved by RADIO BROADCAST -jr 




SUMMER-TIME RADIO 



The super-autodyne described in this issue is made portable by use of the Lynch Lead which connects 
the filaments to the automobile battery. The Crosley " Musicone " is connected by a long cord so that 
the receiver may be left in the car and the speaker taken to any convenient spot nearby. It is grow- 
ing more and more fashionable to make a portable set a part of motoring and camping equipment 




BROADCAST 



Vol. 7, No. 3 




July, 1925 



" Stations Revolutionize 
Radio? 



Senator Marconi's Own Story of His Experiments with Short Waves Increased Effici- 
ency and Greater Sending Speed Made Possible by Focussed High-Power Short Waves 

By GUGLIELMO MARCONI 



THE art of radio communication might 
well adopt as its motto, paralleling a 
well-known Roman saying about 
Africa, "Ex radio semper aliquid 
novi," or, to put it in the vernacular, "Out- 
of radio we are always getting something 
new." , 

For many years, all the important radio 
communication enterprises of the world have 
been engaged in building larger and more 
powerful stations, employing many hundreds of 
kilowatts in order to be able to send forth into 
the ether more powerful and longer electric 
waves, which have, in some cases, reached a 
length of about 15 miles. But had a little 
more time been devoted to a systematic in- 
vestigation of short waves, produced by a 
power equal to only a fraction of that used in 
all of the big stations in the world, the dis- 
covery might have been made that a modest 
loo-foot wave, utilizing only some 15 kilo- 
watts or 20 horse power, could successfuly 
travel from England to Australia and South 
America, even during daylight, and there re- 
produce easily decipherable telegraphic sig- 
nals. 



But most experts, relying on theories which 
had not been thoroughly tested or on insuffi- 
cient experimental data, had made up their 
minds as to what short electric waves could or 
could not do. It was reserved for the years 
1923 and 1924 to show conclusively that such 
short waves could, and did, perform efficiently 
and reliably most of the things which the 
experts had considered until then either im- 
possible or impracticable. 

I think I am justified in saying, as a result 
of the experiments which I have carried on for 
a number of years and which culminated in 
1923 and 1924, that a combination of short 
electric waves with what is known as the Beam 
System, is likely to bring about what amounts 
to nothing less than a revolution in the meth- 
ods of commercial long-distance radio com- 
munication. 

SHORT WIRELESS WAVES ARE HISTORICAL 

THE use of short electric waves is as old as 
the discovery of the waves themselves. 
Hertz made use of them in his first classical 
experiments, and he proved that they obeyed 
the same laws as the infinitely shorter light 



324 



Radio Broadcast 



waves in regard to the speed of propagation, 
reflection, refraction, and diffraction. Some 
twenty-nine years ago in my own first experi- 
ments, in Italy, and shortly afterward in Eng- 
land, 1 used short waves in combination with 
metallic reflectors and, curiously enough, I 
was then able to transmit signals with them 
over a distance of a mile and three quarters, 
while with the elevated antenna and much 
longer waves, i. e., using the same system that 
is used to-day in all the high-power stations of 
the world, 1 could only 
manage to communi- 
cate over a distance 
of half a mile. 

It is perhaps regret- 
table that the subse- 
quent rapid develop- 
ment of the long-wave 
system, which in three 
or four years achieved 
such spectacular re- 
sults, drew away the 
attention of most of 
us not only from the 
possibilities of the 
short waves, but also 
from the use of suit- 
able reflectors to con- 
centrate them into a 
beam in a definite 
direction, which is 
possible only with 
short waves. I never 
quite abandoned the 
idea, however, of uti- 
lizing the latter and, 
in addition, 1 always 
realized the import- 
ance of evolving a 
practical directive 
system of radio com- 
munication. 

I believe it is gen- 
erally admitted now 
that electric waves 

are far too valuable to be always allowed 
to spread out in every direction when it is 
desired to communicate with only one par- 
ticular place. If a station in Great Britain 
wishes to communicate with one in the United 
States, for example, there seems to be no 
good reason why, if it can be helped, what 
it has to say should be heard in Siberia, and 
Egypt, as well as in Nicaragua and India. 
Naturally, non-directional stations, which 
scatter their waves in every direction, are of 
great utility for many naval and war purposes, 



What Senator Marconi Is 



HIS last trip to the United States, 
Senator Marconi presented a paper be- 
fore the Institute of Radio Engineers de- 
scribing various radio experiments bein& 
conducted under his direction. That paper 
was read June 30, 1922, and dealt to a lar&e 
extent with experiments with short radio 
waves. 

It should not be thought that short wave 
radio transmission is new, simply because 
experiment in this field has lately received 
a &ood deal of attention from amateur and 
commercial engineer alike. Senator Mar- 
coni's earliest experiments with wireless 
waves in 1895 and 1896 used waves not 
more than a few inches loh&. A-nd'noWj- 
after radio stations have been built to use 
waves as lon& as 20,000 meters, the cycle of 
radio investigation swings back to something 
very similar to that of the first radio experi- 
ments. But in these experiments, the aim is 
to do away with the fading and absorption of 
signals, interference by natural electric 
waves, and to make transmission directional. 
In this article, Senator Marconi himself tells 
of what he and his engineers have lately done 
to revolutionize radio. THE EDITOR 



and of course for broadcasting, where the very 
soul of the process lies in the fact that the 
waves are scattered all around to be picked up 
by any one with a suitable receiving set. 
But it has always seemed to me that, if possi- 
ble, the right thing to do would be to concen- 
trate the whole of the radiated energy into a 
beam directed toward the locality with 
which it is desired to communicate, just as the 
beam of light waves from a searchlight is thrown 
in one direction by means of reflectors. 

Such a result is 
greatly to be desired 
on many grounds, 
such as the low cost 
of installation and 
economy of upkeep 
entailed by the much 
lower amount of en- 
ergy required, the re- 
duction of interfer- 
ence with other 
stations, and the com- 
parative secrecy 
which can be ob- 
tained. 

Economy of energy 
is a matter which is 
instantly translatable 
into pounds, shillings, 
and pence. I f we con- 
sider a high - power 
station similar to the 
one recently built in 
the Argentine for 
communication with 
Europe over a dis- 
tance of about 6000 
miles, every time the 
operator depresses the 
key and sends a signal 
flashing through the 
ether, some 800 kilo- 
watts (about i 100 h. 
p.) is expended, al- 
though in the case of 

these long waves, only a small fraction of the 
power is radiated from the antenna, which, in 
this case, is supported by ten steel towers each 
690 feet high. It is evident that if a signal 
as easily readable can be sent with 30 or 40 
kilowatts (about 50 h. p.) and by means of an 
antenna supported by much lower and fewer 
masts, there will be not only a greatly de- 
creased cost of installation of the station, but 
also a great reduction in the cost of maintain- 
ing the station. 
With regard to the question of interference 



Will "Beam" Stations Revolutionize Radio? 



325 



with other stations, it should be remembered 
that the number of available wavelengths is, 
after all, far from being unlimited, and if 
Brazil wishes to let New York know the prices 
of coffee and rubber on a certain wavelength, 
it would seem useless and, in certain cases, per- 
haps, undesirable, to broadcast the same in- 
formation over Africa, Europe, the Pacific 
Ocean and probably a large part of Asia. 

BEAM RADIO TRANSMISSION IS MORE SECRET 

AS REGARDS secrecy, the beam system 
possesses a considerable advantage be- 
cause only places situated within a certain 
angle or sector of the beam are able 
to receive a signal sent out by this 
method. This comparative secrecy 
or privacy, which cannot be obtained 
with any other system of radio com- 
munication, might prove of the great- 
est possible value in war time and, 
moreover, as has already been said, 
by reducing mutual interference, it 
will increase the number of stations 
that can be operated within a cer- 
tain area. 

During the early stages of the War, 
1 became convinced that we had per- 



mitted ourselves to get into a rut by allowing 
our attention to be monpolized almost exclu- 
sively by long waves, and 1 decided to take up 
the systematic study of short waves in com- 
bination with arrangements for directing them 
in any given direction. My first experiments 
along these lines in Genoa and later in Livorno 
in 191 6; showed me that good directional work- 
ing could always be obtained with properly 
constructed reflectors, and with the apparatus 
then available a range of six miles was at- 
tained. 

Further experiments, carried out by my 
assistant, Mr. C. S. Franklin, between Carn- 





Kadel & Herbert 

THE " ELETTRA" 

Senator Marconi's floating radio laboratory and pleasure yacht. Much of this great investigator's, most 

important work has been done aboard his yacht. Some of the experiments described in this article were 

made on the Eleitra while she was in the Mediterranean, communicating with the station at Inchkeith, shown 

in the cut on page 327. The insert shows Senator Marconi in his radio cabin 



326 



Radio Broadcast 



arvon, in Wales, and Ireland, and subse- 
quently between Hendon, near London, and 
Birmingham, increased this range to nearly a 
hundred miles and strong radio-telephonic 
speech was received with the use of a power of 
only 700 watts (less than i h. p.)- One very 
important experiment led to the knowledge 
that, when suitable reflectors were used at 
both ends, that is, one reflector to concentrate 
and project the waves in a beam and the other 
to focus them at the receiving end on the re- 
ceiving antenna, the received energy was some 
200 times greater than when no reflectors 
were used. 

The success of these experiments led me to 
carry out a series of tests between a small 
experimental transmitting station at Poldhu 
in Cornwall, and a receiver installed on my 
yacht, the Elettra, which would enable me to 
vary the distance between the transmitting 
and receiving ends at will. Until then, most 
technicians were under the general impression 
that the range of short waves during daytime 
was variable and short, and that though their 
night range was, as a rule, much greater, it 
was far too unreliable to be of any use for 
practical commercial work. In addition it 
was thought that any considerable mass of 
land, especially if it were of a mountainous 
nature, would very materially reduce the 
working range with them. My experiments, 
which were carried out chiefly with waves of 
about 100 meters in length, and with about 
12 kilowatts (about 16 h. p.), served to dis- 
prove a considerable portion of these beliefs 
and theories. 

I knew, of course, like every other experi- 
menter, that short waves, or at any rate 
short waves of the length I was then using, 
had much shorter ranges during daytime than 
at night. This fact was first observed by me 
in February, 1902, and my subsequent dis- 
covery that waves of the order of several 
thousand meters would, on the average, 
work as well by day as by night, was one of 
the main contributory causes to the develop- 
ment of the use of long waves for long-distance 
communication. 

In the 1923 experiments with the Elettra, 
"however, I found that the day ranges were 
reliable and of a quite respectable magnitude, 
that the night ranges were much greater 
than any one, including myself, had expected, 
and that intervening land and large portions 
of continents, mountainous or othe r wise, did 
not prove any serious obstacle to the propaga- 
tion of short waves. I found also, which was 
extremely interesting and important, that 



"day-range" is not an accurate term as the 
strength of the signals received varies def- 
initely and regularly in proportion to the 
mean altitude of the sun over the space be- 
tween the two communicating stations. That 
is to say, the "day-range" depends on the 
particular time of day. 

A TEST AT SEA WITH SHORT WAVES 

WE STARTED off from Falmouth, and 
even when we reached Seville and were 
anchored in the Gudalquivir River, a very un- 
favorable position for reception, as the banks 
of the river were high and covered with trees 
and buildings, we found that the night signals 
were almost as strong as they had been in Fal- 
mouth Harbour, 12 miles from Poldhu, al- 
though at Seville, the whole of Spain, consist- 
ting of over 300 miles of high and mountainous 
land intervened between the sending and re- 
ceiving stations. 

When we reached the Moroccan coast at 
Casablanca, I gave instructions that the re- 
flectors at Poldhu should be set up and we 
then proceeded to the Island of Madeira, and 
finally to St. Vincent, in the Cape Verde 
Islands where, at a distance of 2230 nautical 
miles, we continued to receive the night signals 
with such strength that it was nearly always 
possible to do without an amplifier or to dis- 
connect the antenna or put it out of tune. In 
fact the signals were so extraordinarily strong 
that we never .experienced the slightest trouble 
in consequence of static. The power then 
being used at Poldhu was about 1 2 kilowatts, 
and the reflector so concentrated the energy 
in the direction of the Cape Verde Islands 
that the strength of the signals was such that 
it would have required 1 20 kilowatts at Poldhu 
without the use of reflectors. 

Because I was obliged to return to England 
without going any farther, I gave instructions 
to diminish this power gradually and found 
that with only i kilowatt (about i| h. p.), the 
signals were still stronger than would have 
been required to carry on commercial work 
at night at that distance. It is interesting to 
note that these night signals, received at 
St. Vincent, even when Poldhu was using only 
i kilowatt, were much stronger than those 
which could be received from the high-power 
station at Carnarvon or the British Govern- 
ment station at Leafield (using 200 to 300 
kilowatts) or from any of the other European 
or American high-power stations. 

In view of these rather encouraging results, 
further tests were made early in 1924 between 
Poldhu, using some 17 kilowatts of power and 



Will "Beam" Stations Revolutionize Radio? 



327 




Underwood & Underwood and Marconi's Wireless Telegraph Company 
A REVOLVING BEAM TRANSMITTER AT INCHKEITH, ENGLAND 

One of the experimental transmitters of directed radio energy used by Senator Marconi in his experiments 
between his yacht Elettra and England is shown in the photograph below. The main rigging on the towers 
is used as the reflector, while the transmitting antenna is very short and can be seen just above the two 
blocks at the outside of the circle at the base of the mast. This reflector can be moved so as to "mirror" 
signals in any desired direction. The photograph above shows a model of the beam transmitter used by 
Senator Marconi when he read a paper before the Institute of Radio Engineers at New York several years 
ago, explaining his beam experiments. The transmitting antenna is the short vertical wire at the center 

of the wire "mirror" 




328 



Radio Broadcast 




TRANSRADIO 

The imposing towers of the new international station at Monte Grande, Argentina. The power house and 
masts are the center of the largest international radio telegraph station ever erected in South America. The 
towers are about 690 feet high. The smaller towers in the left foreground form an anchorage for the down- 
leads from the antenna. This station is for communication on long wavelengths and high power. The 
beam method of transmitting has not been applied to this station 



waves of 92 meters and a special receiver in- 
stalled on the White Star Liner Cedric. The 
result showed that during the daytime signals 
could be received up to 1400 nautical miles 
and confirmation was obtained that their 
intensity was dependent on the mean altitude 
of the sun at all times. 

Advantage was taken of these tests to ask 
engineers of our associated companies in 
Australia, Canada, and the United States to 
attempt to listen to these transmissions from 
Poldhu and, rather to my surprise, it was re- 
ported to us from Australia, that they could 
be heard distinctly every day in Sydney, 
from 5 to 9 p. m. (Greenwich time) and again 
from 6.30 to 8.30 a. m., and this with what 
might be called an improvised receiver. If 
we consider the position and the altitude of 
the sun, the preference of short waves for 
traveling over regions not illuminated by the 
sun was made manifest, for it appeared quite 
obvious, that during the morning period, the 



waves traveled over 12,000 miles between 
England and Australia in a westerly direction 
across the Atlantic, America, and the Pacific, 
while during the evening period they must 
have traveled in an easterly direction across 
Europe and Asia, over the shortest distance, 
which is about 9380 nautical miles. 

I was, however, by no means satisfied, for 
one of the essentials of a good telegraph sys- 
tem, whether it be with or without wires, is 
to be able to transmit the messages as soon 
as they are handed in and, therefore, the 
limitation of the period of working to practi- 
cally the night hours constituted an un- 
doubted disadvantage. That this was so, 
admitted of no doubt, so far as 1 had gone. 
For example, although the signals sent from 
Poldhu were received with great strength 
at New York, Rio, and Buenos. Aires when 
darkness existed over the whole or the greater 
part of the track followed by the waves, no 
signals at all were received when the same 



Will "Beam" Stations Revolutionize Radio? 



329 



track or the greater part of it was exposed to 
the light of the sun. Even an increase of 
power or the use of reflectors augmented the 
working hours very slightly. I had the im- 
pression of being faced with conditions ana- 
logous to those produced by a fog on the trans- 
mission of light. If the fog be thick enough, 
no matter how much the luminous intensity 
is increased, the light waves fail to penetrate 
it for any considerable distance. 

DISCOVERIES ABOUT SHORT WAVES IN DAYLIGHT 

I THEREFORE resolved to make further 
1 experiments between Poldhu and the Elec- 
tra, to see if some means could not be found 



to overcome the limitation of working hours 
imposed by daylight. I tried the effect of 
still further decreasing the wavelength, reduc- 
ing it to 60, 47, and, finally, to 32 meters and 
I found that the opaqueness of space in the 
daytime diminished rapidly as the wavelength 
decreased. During these tests, which were 
conducted in August and September of last 
year, the 92-meter wave could not be heard for 
many hours in Madeira a distance of 1 100 
miles entirely over the sea. At Beyruth, in 
the Mediterranean, the 32-meter waves were 
regularly received all day, although the dis- 
tance was 2100 miles, practically all over 
mountainous land. 




THE POWER HOUSE AT TRANSRADIO 

The most interesting thing in this photograph is the antenna radiation meter which registers up to 1200 

amperes. Energy from large radio telegraph stations such as this is radiated in every direction and much of 

it serves no useful purpose. Senator Marconi believes that beam transmission of radio signals on short 

waves will do much to alter the whole course of long distance radio communication 



330 



Radio Broadcast 



Marconi's Wireless Telegraph Company 
A CANADIAN MARCONI TRANSMITTING 

ANTENNA 

Note the high towers in process of erection. Present 
international stations use wavelengths of from six to 
seven miles, while the beam transmitting stations 
will use wavelengths of about 120 feet. POZ at 
Nauen, Germany is carrying on long distance com- 
munication on high power on a wavelength of about 
40 meters, while the stations of the Radio Corpora- 
\\on of America are being equipped to use short 
waves as an auxiliary to their regular long wave 
equipment. Short wave transmitters do not require 
nearly the elaborate antenna installation that the 
present long wave stations do. Senator Marconi 
contends that reflected short waves are much less 
subject to unfortunate fading effects than are the 
long waves 

This discovery was so interesting and satis- 
factory that I thought it wise to confirm it 
over longer distances and, in October and 
December of last year, with only 12 kilowatts 
of power, it was immediately found possible 
to transmit signals and messages from Poldhu 
to New York, Rio de Janeiro, and Buenos 
Aires when the whole of the track separating 
these places from Poldhu was exposed to 
daylight. Poldhu was also able to communi- 
cate with Sydney, in Australia, for a period 
of 23! hours out of 24. 

To sum up my impressions of all these ex- 
periments, 1 can say that I am now firmly 
convinced that the day is fast approaching 
when beam stations, using short waves, and 
employing only a fraction of the power util- 
ized in the present high-power stations, and 
with much lower and fewer masts, will be able 
to carry on communication at practically any 
time between any two points of the earth's 
surface and at much higher speeds than are 



now possible. It should be mentioned here 
that very high speeds appear to be possible 
only with short waves and, therefore, even if 
only a portion of the 24 hours were utilized, 
a much greater number of words could be 
transmitted than would be possible with a 
slow-speed, long-wave service, even should it 
be found capable of working during the whole 
of the 24 hours. It should also be borne in 
mind that, although communication at great 
distances has been obtained without the use of 
reflectors, still 1 am of the opinion that these 
will be found to be essential for the carrying 
on of commercial, high-speed services, be- 
cause, apart from their directive effects, they 
enormously increase the effective strength of 
the signals, thus minimizing the effects of 
what is known as "fading." Reflectors, 1 
find, also increase the margin of readability 
of the signals. 

WE DON'T KNOW MUCH ABOUT THE LAWS OF 
SHORT WAVES 

NATURALLY a good deal remains to be 
done in connection with a further and 
still more systematic study of these short 
waves and the conditions and laws which 
regulate their propagation through space. 
For some time, the practical technical side 
of radio has been far in advance of the theory 
of the subject. We have known a great deal 
about the methods of producing electric 
waves and about the various methods of 
receiving such waves, but our knowledge 
of the conditions that govern their propaga- 
tion through space is far from exact. Other^ 
wise, as I have said, we might have known 
long ago that it was possible to send messages 
to Australia throughout the 24 hours on a 
3O-meter wave with only 10 or 12 h. p. of 
energy in the antenna. 

However, now that this has been ascertained 
and confirmed by numerous experiments, I 
have no doubt that the development of short- 
wave beam stations will be more rapid than 
that of the old super-power stations, and it is 
my firm personal opinion that these latter 
will, sooner or later, be found to be uneconomi- 
cal and comparatively inefficient so far as 
long-distance commercial communication is 
concerned. 

One final point remains to be mentioned in 
connection with these newly discovered prop- 
erties of short electric waves. We may be 
on the threshold of a day when broadcasting, 
that application of radio which interests the 
whole of the civilized world, will have its 
range enormously increased. Within a year 



Will "Beam" Stations Revolutionize Radio? 



331 



or two, the voice of the King of 
England, for example, may be 
easily and clearly heard by mil- 
lions of his subjects in places as 
far apart as India, Australia, 
Canada, and South Africa. A 
service in Westminster Abbey, 
with its sermon, choral and organ 
music, may be clearly heard in 
Capetown. It may become as 
easy to listen-in for the Philhar- 
monic Orchestra in London, as 
it would be now in Philadelphia. 
Perhaps the voice of the short 
wave will be able to accomplish 
for human brotherhood and our 
common civilization what has not 
yet been done by the better- 
known long wave, although radio 
is already one of the most power- 
ful agents in the linking of man- 
kind into one great whole. 



MASTS AT THE CARNARVON, 
WALES STATION 

Of Marconi's Wireless Telegraph Com- 
pany. These tall masts help to con- 
duct the high power long wave radio 
telegraph signals into the ether. Com- 
pare the size of the power pole with 

that of the radio masts. This transmitter spreads its energy in practically every direction while the beam 
station, illustrated below, directs its energy in a beam 





Marconi's Wireless Telegraph Company 

HOW THE POLDHU BEAM STATION WILL LOOK 

High towers support the reflecting antenna while the very short sending antenna is in the exact center of the 
whole structure. The English Marconi Company recently announced that it planned to erect beam trans- 
mitting stations which will link England with all her colonies. The English Company expects to establish 
surer and more efficient communication, using the methods developed by Senator Marconi, which may, 
perhaps, replace the extensive installations now necessary for radio telegraph communication over very long 

distances 




INSIDE THE CRATER OF MT. VESUVIUS 

Professor Rogotti of Milan, with two assistants, transported a radio receiver inside the crater of this famous 
old volcano to test the radio receiving qualities of this somewhat sparcely populated area. The tests seem 
to prove that there was no radio reception near the eruptive cone of the volcano, while at a distance of 300 
feet from the cone, reception was rather poor. The experimenters, as the photograph shows, wore masks 
as a protection against the stifling gases from the erupting cone 




Past President, Institute of Radio Engineers 



How the Propagandists Work in Radio 



UNDOUBTEDLY there are millions 
of people in the United States to-day 
who have a real interest in radio 
broadcasting. Discounting many 
times (as any sensible person unconsciously 
does) the figures given out by over-enthusiastic 



broadcasting managers, we still must place the 
number of these radio folk at some millions. 

The purchasing power of such a number of 
people is tremendous, and is measured, of 
course, in the hundreds of millions of dollars. 
It is natural that some of the radio manufac- 



How Radio Propagandists Work 



333 



turers have reached the conclusion that the 
employment of professional propagandists 
"public relations counsel" is a kinder phrase 
would be greatly to their advantage. These 
gentlemen, honorable, no doubt, draw their 
pay for creating in the minds of the public a 
favorable impression for the man or product 
they write about. Stories at regular intervals 
come from these rather undesirable publicists 
in which their employers are favorably 
featured. These stories frequently find their 
way into the daily press and so appear as 
unbiased news to the casual reader. 

By sheer repetition, one is frequently con- 
vinced that the repeated statement is fact, 
even though no proof has been given. This is 
illustrated by the current belief that four people 
out of five - have 
a certain malady, 
whereas the pre- 
valence of this 
trouble is un- 
doubtedly greatly 
exaggerated in the 
well known adver- 
tisements. If one 
reads enough sto- 
ries, each begin- 
ning with, Mr. A. 
B. C, the well- 
known radio engi- 
neer and inventor, 
one is quite likely 
to think that the 
man in question 
is a radio engineer 
and inventor, when 
that may not be 
the case at all. 
Then if the story 
gives Mr. A. B. 
C.'s ideas on a 
certain radio sub- 
ject one is likely 
to think that an 
authoritative, un- 
biased opinion is 
being presented, 
when as a matter 
of fact, the gen- 
tleman in question 
is simply succeed- 
ing in a bit of in- 
direct advertising. 

So prolific are 
the writers of this 
type that the ra- 
dio editors of our 



newspapers never lack material with which 
to fill their daily columns. One of our friends 
recently offered to write for a certain paper 
a series of popular articles dealing with the 
relative merits of different receivers on the 
market, showing how they worked, why one 
was more selective than the other, another 
good only for local reception and still another 
preferable for distant stations, etc. He was 
told by the radio editor, however, that in- 
stead of paying for radio articles, he had quite 
a task in selecting his stories from material 
which was sent in voluntarily. 

To the best of our knowledge, there are very 
few men writing stories (even radio ones) 
to-day for the mere love of writing. We 
should like to suggest that when next you read 




\ 



A WIRELESS-EQUIPPED LIFEBOAT 

Aboard the S. S. Orbita. The British Board of Trade has ruled that to every ten 
lifeboats aboard large passenger ships, there shall be one lifeboat with radio trans- 
mitting and receiving equipment. The operator has a small cabin 'way up fo'ard. 
The transmitter has a range of about 100 miles. A small two-wire antenna is used. 
In the bow of the boat is the rectangular loop used in the direction-finder equipment 



334 



Radio Broadcast 




8616- 



JLJL 



ARCHITECT S DRAWING OF A PROPOSED 

BUFFALO STATION 

Which incorporates some new ideas in station design. The towers 
rise 60 feet above their pyramidal pedestals, whose design was 
suggested by a pyramid built in Guatemala many thousands of years 
old. The broadcasting station has been designed especially for 
the new Liberty National Bank building at Buffalo. Alfred C. 
Bossom, of New York is the architect 



one of those interesting interviews with "Mr. 
A. B. C. the well-known radio engineer and 
inventor," you ask yourself first whether he 
really is such a well-known engineer and next 
why he said that a crystal was better for a 
detector than a tube, etc. Just possibly his 
revenues will be increased if you direct your 
purchases along the line he suggests. 

Super Power Is Almost Here 

A MOST as soon as this magazine appears, 
the new broadcasting venture of the 
Radio Corporation will be launched. 
At Bound Brook, New Jersey, the Cor- 
poration has erected its first high-powered 



broadcasting station, and we un- 
derstand that, opening some time 
in June with a moderate power 
output, this station will gradu- 
ally increase its power until its 
full output of forty to fifty kilo- 
watts is reached. Familiar wjz, 
which was first berthed in New- 
ark, New Jersey and was later 
transferred to the heart of New 
York City, is now to migrate to 
Bound Brook, the while with 
greatly increased output. 

It is our belief that the op- 
eration of high-powered stations 
such as this, is one of the real 
solutions for static. This ever- 
present disturbance does not 
greatly bother those of us who 
are within perhaps twenty-five 
miles of a low-powered station, 
but for those more than a hun- 
dred miles away from one of our 
present 5OO-watt stations, the 
pulses of static are at least as 
strong as the signal during parts 
of the year. During a few of 
the summer months, the static 
noises are so loud that they 
make a program from the dis- 
tant station unsatisfactory. 

As the various static elimina- 
tors come forward and then 
quietly retire from the radio 
stage, we can find no evidence 
of defeat or even fatigue in our 
atmospheric disturbances. The 
only evident remedy to circum- 
vent nature in her pernicious in- 
terference is to greatly increase 
the strength of the radio signals, 
to drown out static. That will 
require a great many kilowatts 
of power, as wjz anticipates using. We shall 
all watch with great interest the public's reac- 
tion to the new venture. 

Again it is to be pointed out that those radio 
listeners near the high-powered station will 
naturally have some difficulty in tuning it out 
sufficiently well to hear distant stations of 
nearly the same wavelength. This tuning 
difficulty will be true of the average set as used 
to-day. It will be possible, however, to build 
special rejector circuits which will greatly 
cut down the wjz signals even for those in 
its immediate vicinity. Undoubtedly a re- 
jector circuit for a reasonable price will be 
put on the market. 



What is a "Bootleg" Tube? 



335 



m- 



1 he Crime of a Radio Manufacturer 

JUST as we had thought the single-circuit 
regenerative receiver was beginning to dis- 
appear from the market we learn from a 
most reliable source that an order for about 
one hundred thousand of these receivers is 
being put through the shops of one of the larg- 
est radio manufacturers. One hundred thou- 
sand more potential squealers from one manu- 
facturer is a frightful stop to radio progress. 
This is no step forward in the march of radio. 
It looks as though this manufacturer was more 
interested in dividends than in the advance- 
ment of the art. 

What Is a "Bootleg" Tube? 

A ONE after another of the vacuum 
tube patents expire, it becomes 
creasingly diffi- 
cult to say just what is 
a bootleg tube and 
what isn't. While 
Fleming's valve patent 
and De Forest's three- 
electrode patent were 
still running their 
seventeen-year life, it 
was an easy matter to 
distinguish between 
genuine and counter- 
feit tubes. But now 
with the fundamental 
three-electrode idea 
thrown open to all, 
(the patent expired in 
February) one has to 
look more carefully to 
see if a tube is infring- 
ing those design patents 
and others which still 
have some time to run. 
Before a manufac- 
turer invests much 
money in the business 
of tube making, he 
would do well to con- 
sult some patent at- 
torney who is closely 
in touch with this par- 
ticular field. There are 
many patents on the 
details of construction 
which may still be in- 



probably not possible for any manufacturer but 
the Radio Corporation to make tubes whose 
filaments are made electronically active by 
the addition of thorium. There may be other 
ways of making even better tungsten. It 
seems quite possible that European tubes are 
made sensitive by some other process, and if 
so, such a process may become available to 
independent manufacturers here. Schemes 
used for attaining this high vacuum are fully 
patented. The difficulties of properly exhaust- 
ing tubes frequently are so great as to cause the 
downfall of the inexperienced manufacturer. 
There is one very interesting phase of the tube 
situation which has still to be settled. Years 
ago, the American Telephone and Telegraph 
Company and the General Electric Company 
were involved in a very seriously contested 
suit having to do with the question of degree 




fringed. The sensitized 
tungsten which is used 
in the modern tube is a 
patented product. It is 



LIEUTENANTS McCORMICK AND FLOOD 
United States Army, looking over their receiving apparatus which was of con- 
siderable aid during the recent national balloon elimination race. The race 
was won by Ward T. VanOrman. Broadcasting stations near the air course 
broadcast special weather instructions and metereological information to the 

racers 



336 



Radio Broadcast 



of vacuum used in triodes. Doctor De Forest, 
several times, apparently, had admitted the 
advantage of some gas in his audions so that 
the question of a tube having very high va- 
cuum was still unsettled. Doctors Langmuir, 
of the General Electric Company, and Arnold, 
of the Western Electric Company, both had 
patent applications for high vacuum tubes 
whose vacuum was so high that whatever gas 
was present played no important role in the 
functioning of the tube, as it generally did in 
the De Forest audion. Most extensive testi- 
mony was taken and intricate experiments 
were performed before the court to illustrate 
the effect of small amounts of various gases in 
vacuum tubes. 

On a case like this, a judge has a hard time 
in reaching a reasonable decision, and in this 
case no decision at all has yet been reached. 
The court has first to determine whether a high 
vacuum of this sort is patentable, and then if 
it is, to whom the patent should issue. And 
this question of high vacuum is not as easy as 
one might think. The "gas" tube, for ex- 



ample, might be claimed as high vacuum be- 
cause there is only about one hundred mil- 
lionth of the original amount of gas left in the 
tube. But the high vacuum expert comes 
along and tells the judge that although only 
one hundred millionth of the original gas is 
left in the tube there are still ten thousand 
million gas molecules per cubic centimeter 
left in the tube! In such a dilemma, what was 
the judge to conclude? 

This high vacuum patent, if it should ever 
be granted, would most seriously affect the in- 
dependent manufacturer. In fact, should the 
court decide to grant a patent of this kind 
for seventeen more years, the Radio Corpora- 
tion or the American Telephone and Telegraph 
Company would completely control the tube 
situation. We regard that control as lament- 
able because we still remember the $6 we 
used to give for Radio Corporation tubes until 
the De Forest patent was about to expire 
when bootleg tubes appeared more plentifully 
with the resultant cut in selfing price of 3 
to i. 




AT WELLESLEY COLLEGE 

Wellesley, Massachusetts, some of the advanced students in the Physics Department are learning something 
about radio. Left to right: Miss Lucy Begeman and Miss Louise McDowell, instructors of radio in the 
Physics department of the College; Miss Truko Nakamura, Tokyo, Japan; Miss Jane Whigham, Pittsburgh; 
and Miss Ruth Lovejoy, Boston. The essentials of a fifty-watt continuous wave transmitter are being 

assembled 



Extravagant Radio Claims Are Not Legal 



337 




K. INUKAI 
Japanese Minister of Communications, listening to a Tokio radio program with members of his family 



Radio Sets Must Meet the Claims 
Made for Them 

A MOST commendable decision was re- 
cently handed down by Judge Woester 
in the Municipal Court of Cincinnati. 
A radio supply house had sold a five-tube set 
with the guarantee that it would "get" all 
the stations from coast to coast. The user 
claimed that the set did not bring in every 
broadcaster and he refused to pay for it and 
was subsequently sued. 

The Judge ruled that if the set was guaran- 
teed to do certain things it must live up to 
its guarantee. If the claims were not met, 
the purchaser was not obliged to pay the 
price specified. It was argued that the pur- 
chaser didn't have a good ground or antenna; 
the plaintiff evaded the obvious confession, 
that his claims for the operation of the set 
were extravagant. It would be a good thing 
to have a few more decisions of this nature on 
record. We think that then dealers and sales- 
men might be more careful about their en- 
thusiasms. It may be that the ruling of the 
Municipal judge will be reversed when the 
case is carried to the higher courts, but we 
hope not. Absurd and extravagant claims of 
radio salesmen have far too often resulted in 
the disappointment of the purchaser. 



The Associated Press Recognizes 
Broadcasting 

DURING the recent annual meeting of 
the Associated Press in New York this 
conservative organization yielded to 
the pressure of the modernists within its ranks 
and decided to make radio broadcasting one of 
its many allies. The great national interest 
in the broadcasting of the last presidential 
election was the lever used to upset the con- 
servatives. By a vote of 130 to 10, the As- 
sociation decided to permit its dispatches to 
be used over radio channels when the items 
can be regarded as of "transcendent import- 
ance." 

The resolution which admits radio as a 
friendly arm of the Association was as follows: 

Whereas, the tremendous and continuing growth 
of radio broadcasting is presenting many new prob- 
lems not contemplated when the existing by-laws 
and rules of The Associated Press were adopted; and 

Whereas, the great public interest in the result of 
Presidential elections and other events of nation- 
wide importance has repeatedly raised the question 
of the advisability and wisdom of permitting the 
limited and restricted use of Associated Press matter 
in the broadcasting of such special and outstanding 
events; therefore be it 

Resolved, That the Board of Directors be author- 
ized to adopt the necessary rules and regulations 



338 



Radio Broadcast 



which shall permit the broadcast of such news of the 
Association as it shall deem of transcendent national 
and international importance and which cannot by 
its very nature be exclusive, provide adequate safe- 
guards, and require that proper credit in each and 
every instance be accorded the Associated Press. 

The great activity of the Associated Press, 
with its 1 195 newspaper members, is indicated 
by the treasurer's report which showed an 
income during the past year of more than seven 
million dollars. 

At about the time that the "A. P." was tak- 
ing this action on radio, the American News 
paper Publishers' Association was also taking 
cognizance of this newest method of communi- 
cation, endeavoring to eliminate propaganda 
and direct advertising from the radio channels 
conducted by the newspapers. The resolution 
passed by the publishers was as follows: 




SCIENCE INVADES THE CHURCH 

The microphone an excellent symbol of modern progress suspended over 
the famous carved pulpit of Notre Dame de Paris. The pulpit was 
designed by ViolIet-le-Duc. The microphone is not for broadcasting but 
for the public address system which has just been installed in this famous 
old cathedral 



Whereas, direct advertising by radio is likely to 
destroy the entertainment and educational value of 
broadcasting and result in the loss of the good-will 
of the public, therefore be it 

Resolved, that members of the A. N. P. A. refuse 
to publish free publicity in their news columns con- 
cerning programs consisting of direct advertising; 
also that they eliminate from program announce- 
ments the name of trade-marked merchandise or 
known products obviously used for advertising, and 
that newspaper broadcasters eliminate all talks 
which are broadcast for direct advertising purpose. 

The Victor Company Joins the Radio 
Ranks 

THE phonograph companies have, one 
by one, yielded to radio. The recent 
annual report of Eldridge P. Johnson, 
president of the Victor Talking Machine 
Company, announces the 
future radio activities of 
this company. "Plans care- 
fully and deliberately de- 
veloped toward meeting the 
conditions confronting the 
industry are rapidly nearing 
maturity, and are antici- 
pated to maintain your 
company in its position in 
the van of the entertain- 
ment field." These "condi- 
tions" of course, are the 
effects of the popularity of 
radio receivers on the sales 
of talking machines. We 
may expect the Victor or- 
ganization to make an ex- 
cellent impression on the 
public when they do enter 
the radio field. The won- 
derful entertainment their 
artists gave us last winter 
through WEAF, and other 
stations, would permit 
nothing else. 

There is a fine opportu- 
nity for the marketing of an 
artistic high quality loud 
speaker. Rumor has it that 
the Victor Company has 
secured the patent rights to 
a loud speaker developed 
and patented in France. 
Some European engineers 
have spoken of this talker 
as better than anything 
we have in America, and 
if this is true, we certainly 



The World Conference of Amateurs 



339 



would like to see it put on the market 
here. 

We sincerely hope that the new policy of the 
company will not interfere with continued 
concerts by their artists, as it is impossible at 
this time to imagine a better combination 
than the artistic talent of the Victor perform- 
ers and the technical excellence of the broad- 
casting apparatus of the American Telephone 
and Telegraph Company engineers. 

There Are So Few American Radio 
Tubes 

IN A recent issue of the Wireless World 
(London), editorial dissatisfaction is ex- 
pressed with the number of tubes now on 
the English market. So many experimental 
and war type tubes as well as more standard 
recent ones are available to the radio experi- 
menter, that many times he buys tubes en- 
tirely unsuitable for his work. Improvement 
would be brought about, according to Hugh S. 
Pocock, the editor, if most of the types were 
withdrawn from the market, leaving only two 
or three standard types. 

If we in America have any difficulty of this 
sort, it is rather on the opposite side. We 
really have only two types of tubes for re- 
ceivers on the market; the quarter-ampere 
5-volt filament, and the sixteenth-ampere 
3-volt filament. The latter is hardly to be 
regarded as a success because of its fragility 
and short life. In Holland, a Dutch engineer 
recently told us, the Phillips Lamp Works is 
putting on the market a tube which he regards 
as the equal, if not the superior, to any of our 
tubes. The Dutch tube uses in its filament 
circuit a sixteenth of an ampere at one volt, 
that is, just one third the power which ours 
uses. We would welcome this Dutch tube to 
our present small assortment. The tube 
which uses alternating current in its filament 
and operates from a light socket, is surely on 
its way. The so-called McCullough A C tube 
built on this principle, has recently been an- 
nounced and just as sure as the public takes 
to this tube, the Radio Corporation will put 
out one to equal or possibly surpass it. 

We sincerely hope that the McCullough 
tube has been so carefully built that it will not 
fail, and thus give this desirable type of tube 
a bad reputation before it has been even well 
tried out. In a new development of this kind 
it is very easy to make technical and manufac- 
turing errors, and so give a product a bad name 
when more care and study would have made 
it a complete success. We certainly extend 




Harris & Ewing 
W. E. DOWNEY 

Technical radio expert of the Bureau of Navigation, 
Department of Commerce. On Mr. Downey's 
shoulders fall much of the technical advisory work 
which is a constant necessity in the administrative 
branch of government radio control 



to this first alternating current tube our very 
best wishes. 



The World Conference of Amateurs 

THE first world conference of amateurs 
has just come to a close. And thinking 
of this world union, the amateurs may 
well feel that progress is being made. Ten 
years ago, the American Radio Relay League 
was just starting; now its members are num- 
bered in many thousands and they assume a 
commanding role in any international question 
having to do with radio amateurs. 

The conference recommended wavelength 
assignments for the amateur channels as fol- 
lows: United States, 85 to 70 meters and 41 .50 
to 37.50; Canada and Newfoundland, 120 to 
1 15 and 43 to 41.50; Europe, 1 15 to 95, 75 to 
70, and 57 to 43; other countries, 95 to 85 and 
37.50 to 35. These short wave channels, of 
course, must be approved by the respective 
governments concerned before becoming the 
official domain of the amateurs. 

It is interesting to note how important the 
short wave channels are becoming. American 
British, and German commercial companies 
are all carrying on intensive experimentation 
in the development of transmitters and re- 
ceivers for these nearly ten million-cycle 
currents. The German station POZ, for exam- 
ple, is working to Argentine with a 4i-meter 
channel, and it won't be long before the five- 



340 



Radio Broadcast 



or ten-turn coil, a couple of inches in diameter, 
becomes recognized as a regular tuning coil. 

We cannot urge too strongly that the ama- 
teurs get busy with their short wave receivers. 
As this issue goes to press, Donald MacMillan 
is leaving the country for his next polar trip. 
In view of the fine showing made by short 
wave communication on his last trip, Mr. Mac- 
Millan has decided that his outfit this time 
will be short wave equipment altogether, and 
he has indeed chosen a short wave expert to 
accompany him, in John L. Reinartz of South 
Manchester, Connecticut. 

Plans for the expedition include the trans- 
mission of a daily resume of their activities and 
findings, sent out at noon on a 2O-meter wave. 
Recent successful daylight transmission with 
these extremely high frequency currents lead 
to the belief that the signals will be picked up 
at Washington where the government services 
will be listening, and thus permit a rebroad- 
cast on ordinary wavelengths. 



Work for Hoover's Third Radio 
Conference 



s 



ECRETARY HOOVER is again con- 
templating calling in the best radio minds 
in the country for a third annual confer- 
ence. 

The possibility of such a call was considered 
by the conference of the Radio Committee of 
the League of Nations which has been in ses- 
sion in Geneva. It was anticipated in Geneva 
that the Washington call would not come until 
the spring of 1926 at the earliest. This com- 
mittee decided to call to the attention of the 
Washington conference the necessity of elab- 
orating the international regulation of radio 
communication concerning security at sea 
and the protection of navigation. It has not 
been apparent that commercial radio has se- 
riously interfered with the channels reserved 
for navigation and distress messages, but it 
may be that the problem in European waters 
is more serious. If this is so, the Washington 
Conference would do well to consider it. 



The Month in Radio 



N GERMANY it is a crime to listen-in on 
broadcast programs unless the government 
fee has been paid, and according to a press 
dispatch, there are more than 550,000 obedient 
citizens who pay the Post Office Department 



about fifty cents a month for their radio en- 
tertainment. At present the government re- 
ceives more than three million dollars annually 
from the radio enthusiasts. 

MORE than three years ago, in fact in our 
very first editorial, we suggested that phil- 
anthropists should leave money for equipping 
and endowing high class broadcasting stations. 
This movement had its inception at the Uni- 
versity of Notre Dame and the University of 
Illinois, both of which are to be given modern 
stations as memorials to Roger C. Sullivan, 
a well-known Democratic leader of Illinois 
who died five years ago. The stations are 
gifts from his son, B. H. Sullivan. This is a 
fine beginning of a worth-while enterprise. 

THE Radio Corporation's quarterly report 
shows its gross earnings for the quar- 
ter ending March 315! to be more than 
$15,000,000. This indicates a total for the 
present year at the same rate of $61,000,000 
or about $6,000,000 in excess of last year's 
business. 

I AST month saw the exportation of some of 
kf America's good radio capital. Dr. Ma- 
rius Latour, a French scientist, owns many 
patents on details of radio receivers, some 
of which have been used promiscuously by 
American radio concerns, who were appar- 
ently all oblivious of his patents. In a suit 
which he brought against the Hazeltine Cor- 
poration, Latour was successful in sustaining 
his claims, so this radio company, and several 
others decided to capitulate and buy him out. 
One of his patents covers the use of iron cores 
in radio transformers. No sensible engineer 
ever thought of using anything but iron cores 
insofar as we know, yet Latour was able to get 
a patent on the idea. Most of his other patents 
are of similar import, but, lacking as they may 
be in scientific merit, they were sufficiently 
important to cause our American companies 
to part with several hundred thousand dollars. 

A CCORDING to newspaper stories, the 
* General Electric Company recently dem- 
onstrated the operation of a loud speaker 
from a crystal set. From the layman-writer's 
description it appears that the instrument is a 
cross between the large paper cone speaker 
and a French type using a small, flexibly sup- 
ported, rigid cone. Needless to say a crystal 
set must be very close to a transmitting station 
if a loud speaker is to be operated by it, be- 
cause at any appreciable distance, the receiv- 



What People Say About Radio 



ing antenna cannot pick up enough power to 
give audible sounds in any loud speaker. 
With tube sets, the local B battery gives the 
energy to operate the loud speaker. The re- 
ceived signal merely serves to control this 
energy. 

SOME interesting figures on the income of 
broadcasting stations were given out re- 
cently by the Radio Artists' Association. Ac- 
cording to their report, some stations are ac- 
tually making money. WHN of New York, 
for example, has a reputed income of $300,000 
a year and expenditures of not more than 
$50,000 a year. WFBH in the same city, has 
contracts which bring in $90,000 a year with 
an annual expenditure of $35,000, it is reported. 
The stations in present Telephone Com- 
pany network charge as follows: 

WEAF $500 per hour, $195.35 per quarter hour; 
WEEI, WJAR, and wcco $250 each per hour; woo, 
WFI, WCAE, WGR, wsAi, and wwj $200 each per 
hour; WCAP, WEAR, and woe $150 each per hour. 
For the "facilities" of all these stations, the gross 
charge is $2600 per hour. To give a ten minute 
talk over this wire-radio network would cost $1300, 
or about a dollar per word. 

The manager of WHN, when shown the re- 
port characterized it as a gross misstatement, 
and similarly, WFBH'S manager claimed that 
his income was only just sufficient to meet 
expenses. 



Interesting Things Interestingly 
Said 



DAVID SARNOFF (New York; vice-president 
and general manager of the Radio Corporation 
of America): "At present it cannot be said that ad- 
vertising over the radio is parallel in effectiveness 
with advertising in periodicals and newspapers. 
The standards of periodical and newspaper adver- 
tising should also apply to the standards of the air 
and no advertisement should be broadcast without 
the plain advertising label." 

HARRY M. WARNER (New York; president, 
Warner Brothers, a motion picture company): 
"My attention has long been directed to a general 
tendency to fight radio within the amusement field. 
The identical arguments used only a few years ago 
in an effort to minimize the popularity of motion 
pictures are being dragged out and pointed at an 
entertainment which now, roughly, has 20,000,000 
supporters in the United States. . . . The cry 
of 'the pictures will ruin the theatre,' is within easy 
memory. But they didn't, although there is no 
doubt that the pictures inflicted considerable dam- 




POWEL CROSLEY, JR. 

-Cincinnati; Radio Manufacturer- 



"/ am looking forward to the day when first class 
broadcasting stations will use from 50 to too 
kilowatts. I believe that this is as essential as 
it was for the commercial companies figuratively 
to boost the power of the original f kilowatt 
used by Marconi when he sent the famous letter 
"s" across the Atlantic Ocean to 50 kilowatt; 
and later, to 200 kilowatts, for satisfactory trans- 
oceanic communication. The high power broad- 
casting stations of the future must be located 
away from large centers of population so as not 
to cause undue local interference. 

" The quality of service rendered by the higher 
powered stations should be recognised by the 
Department of Commerce in assignment of wave- 
lengths, and this recognition should necessarily 
have coupled with it, certain requirements as to 
quality of service. . . . There must be more 
recognition of quality of service and priority 
than there has been heretofore. First class sta- 
tions should not be asked to divide time with third 
class ones. . . . Though still untried, I be- 
lieve more strongly than ever in super-power" 



age to the cheaper theatrical attractions. . . . 
To this has been added the alarm, 'the radio will 
ruin the theatre and pictures.' It will not, provided 
it is used intelligently. . . . The radio is here 
to stay just as the theatres and pictures are here to 
stay. They all have their followers, and just as the 
picture audience is a theatre audience, so is the radio 
audience largely a picture audience. ... To 
my mind, any effort to fight an entertainment that 



342 



Radio Broadcast 




Underwood & Underwood 
CAPTAIN A. W. STEVENS 



New York; Aerial Photographer with 

the Rice Expedition in Brazil 

"Although we worked with portable radio appar- 
atus in the heart of the world's greatest forest, we 
established a record in short-wave communication 
with England. Long-wave communication was 
carried on between the expedition and Manaos 
and short-wave communication to many parts of 
the world, including New York, San Francisco, 
London, Rio de Janeiro, and New Zealand. The 
signals were reported as very strong, both in New 
York and London. Part of the apparatus was 
designed and assembled on the fob by the opera- 
tors, John W. Swanson and Thomas M . Mc- 
Caleb. 

" The antenna system was often erected by saw- 
ing down a number of large trees in the forest 
and stringing the wires between other tall trees 
on the edges of the roughly cleared space. A wire 
was usually strung from the folding table that 
held the instruments to a ground loop." 



has the backing of 20,000,000 people is sadly mis- 
directed and will react harmfully on the entire in- 
dustry. If radio has had an effect on motion pic- 
tures as those exhibitors who should know what 
they are talking about claim my idea is not to 
wage a useless fight against it, but to use radio to 
the best possible advantage." 

N. P. VINCER-MINTER (London, England; 
in an article in the Wireless World}: "From a 
point of view of artistic appearance, American-made 
radio sets show a marked superiority over those 



made in England. In this respect we are not re- 
ferring to the hundred-guinea type of cabinet set, 
whose artistry cannot, of course, be denied, but to 
the ordinary type of good quality set which sells at 
prices ranging from 20 to 40 or thereabouts. 
. . . One has only to glance through the adver- 
tisement pages of any of the American radio journals 
to note the large number of really efficient and 
attractive-looking sets at not unreasonable prices, 
to be acutely aware of how much greater is the range 
of choice accorded to American purchasers. Al- 
though, of course, some of the claims made in these 
advertisements are typically American, it must be 
admitted that on the whole the sets are highly 
efficient." 

BRUCE J. A. M. ELDER (Sydney, Australia; 
Commissioner for Australia in the United 
States): "Production costs have increased enor- 
mously, until now wages in the tailoring trade are 
300 per cent, above the pre-war level. Factory ex- 
penses have also doubled. . . . But there are 
other factors equally important. In the United 
States, there are more than 17,000,000 motor cars, 
which exceeds the number of telephones. These 
cars are bought on time payment as are also the 
majority of wireless sets in the country. I am of 
the opinion that the purchasers of cars and radio 
sets meet obligations by saving on clothing for 
themselves, their wives and families. Radio causes 
people to stay in their homes, thus lessening the 
demand for clothing. American bankers go further 
and say that people do not wear good clothes in 
motor cars and consequently purchase new clothes 
less frequently." 

COWARD H. JEWETT (Detroit, Michigan; 
*-> president of the Jewett Radio and Phonograph 
Company): "Time was when open cars were all the 
rage and most autoists stored their cars during the 
winter. . . . Radio has developed similarly. 
From a purely winter instrument it has been 
brought to the point in development thanks to the 
fine engineering talent in the radio industry where 
it affords the radio enthusiast a full year's pleasure 
and utility. . . . Mighty few vacationists will 
be without their radio this summer. Modern port- 
able sets are as easily taken along on a summer 
journey as the ordinary suitcase. The summer 
camper may pick the wildest, loneliest spot for his 
vacation and yet be in touch with the world through 
his radio." 

S. H. MAPES (Chicago, Illinois; vice-president 
and general sales manager, Joseph W. Jones 
Radio Manufacturing Company) : " Is the possibility 
of extensive improvements in radio sets affecting 
sales? The answer is an emphatic no. For the 
improvements that will come will be those of 'evo- 
lution rather than revolution.' . . . Radical 
changes will not be made, but refinements will con- 
tinue to appear as they have in the automobile and 
other industries. The more noticeable changes will 
be made in transmitting and not in receiving sets." 



'CHe Listeners' Point 




JENNIE IRENE MIX, who has written 
"The Listeners' Point of View" since 
April, 1924, died suddenly after a short 
illness at her home in Toledo, Ohio on April 
26th. 

When "The Listeners' Point of View" 
started it was the first attempt to present 
sound radio program criticism in any maga- 
zine. Miss Mix was probably better qualified 
than any other writer who could have been 
selected for the task. For many years she had 
been writing music, thinking music, and almost 
living it. She was well known in the musical 
life of Pittsburgh. From 1904 to 1918 she 
was music critic of the Pittsburgh Post. 
During many music seasons she covered impor- 
tant musical events in Boston, Philadelphia, 
Cincinnati, Cleveland, Ann Arbor, and 
Chicago. 

Miss Mix spent some time abroad, where she 
furnished music correspondence to a number of 
prominent American newspapers from such 
centers as Paris.jBerlin, 

Munich, Dresden, and ^^^^^^^ 
Bayreuth. In 1920, 
Henry Holt and Com- 
pany published a novel 
from her pen, At Fame's 
Gateway, which deals 
with the life of a young 
music student in New 
York. Comment on 
this book was very 
favorable and very 
widespread. Several 
years before, Miss Mix 
had turned her talents 
in another way and 
Mighty Animals, pub- 
lished by the American 
Book Company, pre- 
sented in an entirely 
new fashion the story 
of prehistoric animals. 
The preface to this 




Jennie HJrene 

26, 1925 



volume was written by Dr. Frederick A. 
Lucas, director of the American Museum 
of Natural History. The book is used as a 
supplementary reader in public and private 
schools. 

A woman of striking personality, Miss Mix 
had a peculiar talent for transferring her 
personal charm to her work, which was one 
reason for her great popularity with the readers 
of RADIO BROADCAST. It is interesting to 
note, also that, in the newspapers, her writings 
were almost as widely quoted as those of 
Professor Morecroft in "the March of Radio." 
Miss Mix felt that, since the greater part 
of radio broadcasting was music, helpful cri- 
ticism and comment about radio music would 
be welcomed by interested radio readers 
everywhere. She had a wide acquaintance 
among musicians throughout the country, and 
she spent many a musical season in New 
York covering the events for newspapers in 
various parts of the country. In "The Lis- 
teners' Point of View," 

i^"^^^^"^^" she was singularly suc- 
cessful in presenting 
comments about radio 
broadcasting programs 
which could be found 
nowhere else. Her re- 
marks on programs and 
personalities, her news 
and comment on the 
new world of radio, 
made for her and for 
RADIO BROADCAST 
many firm friends. 

The Listener's Point 
of View will be con- 
tinued in the magazine 
as before, and the new 
conductor of thedepart- 
ment will take up Miss 
Mix's duties in the 
August number of RA- 
DIO BROADCAST. 




in Interesting Answer to the Question, "How Can I Leanr 
lore About Radio?" What the Colleges Offer The Place 
Value of the Commercial Radio School Some Help and 
Suggestion for the Earnest Student Who Works at Home 

BY KEITH HENNEY 



OF ALL the many questions that 
come to RADIO BROADCAST there 
is one that causes the Editors 
more than usual thought. The 
query of "How can 1 become a radio en- 
gineer?" seems to worry a great variety of 
people. High school students contemplating 
their college courses, mature engineers, me- 
chanical, electrical, civil, chemical or mining, 
and professional electricians; all want to 
know how to fit themselves to enter the radio 
engineering field. And aside from those who 
actively plan a dash into the land of radio there 
are many who would like to know more about 
this fascinating subject than most of the 
present day radio books tell them. They are 
doctors, lawyers, ministers, and the great 
army of tradespeople who are interested in 
radio, and who are interested, incidentally, 
in the whole vast field of science, for its own 
sake. 

And while it is not the purpose of the writer 
to argue the point here of whether there is or 
is not a future for a man fitting himself to be a 
radio engineer, it is well to call attention to two 
conflicting statements appearing in the press 
within the last year. 

According to Colonel Percy E. Barbour, 



Editor of Mining and Metallurgy, the engineer- 
ing field is already overcrowded, and he takes 
exception to the press report that colleges 
and universities are falling behind in their out- 
put of capable engineers. 

The other statement may be found in some 
radio school advertisements wherein the mar- 
vellous salary of $10,000 a year appears in 
large type, and one gets the idea that such a 
munificent sum may be commanded within 
a few months after completing some particular 
course which the school offers. 

It is very difficult to judge the truth of the 
first statement, but it is certainly true that 
any capable wide-awake engineer may find a 
position if he has the qualifications mentioned 
later in this article. The. engineering pro- 
fession, like all other walks of life, needs big 
men, and this means those who have fitted 
themselves with all of the modern educational 
equipment. 

As for the $10,000 year salary, it is again 
largely a question of the man. No student 
who follows any radio course, whether in 
college or by correspondence can hope to at- 
tain this sum unless he has the most extensive 
experience behind him. And that entails 
work, several years of it at least. 



What Are the Royal Roads to Radio? 



345 



WHAT IS A RADIO ENGINEER? 

IN THE first place, as Professor Morecroft 
pointed out in RADIO BROADCAST in July, 
1924: 

"To the best of our knowledge, none of the 
good technical schools of this country confer 
the degree of 'radio engineer.' " 

The nearest approach is that given by Har- 
vard University and other large institutions 
which have a number of courses grouped under 
the title of "communication engineering" but 
here, as in other branches of electrical en- 
gineering, the first degree given after four 
years of study is "bachelor of science in 
engineering." 

The degree of electrical engineering " E. E." 
is usually won only after the bachelor's degree 
has been taken and after at least two years of 
commercial experience. 

A real radio engineer- will probably be proud 
of the fact that he has had a technical training, 
but he will hesitate to admit that he is a radio 
engineer, so thickly populated has the radio 
profession become with self-labelled authori- 
ties without training 
or experience beyond 
that of any boy who 
has assembled radio 



apparatus. 

The field of radio 
engineering is simply 
a branch of electrical 
engineering. A power 
engineer, a telephone, 
or a telegraph en- 
gineer must first of all 
be an electrical en- 
gineer, and a good 
one too. In nearly 
every case, one must 
have a general en- 
gineering training be- 
fore he can specialize 
in any of its many 
branches. 

THE STRAIGHT AND 
NARROW PATH 

THE young man 
who is anxious to 
fit himself best for the 
radio world, should 
learn all he can from 
elementary books 
which he can secure 
in the public library, 
and from actual ex- 



There Isn't Any Formula 



FOR success in any line of activity. 
Not very long ago, someone set down 
three rules for mental progress. They are: 
"i. Sit down in front of a blank wall. 
2. Ask yourself difficult questions. 3. An- 
swer them." And so with radio. The best 
way to learn more about radio is to learn it. 
However, there are so many who really want 
helpful and definite suggestions about how 
they may improve their radio knowledge, 
where good college courses in radio are to be 
had, and what books to read, that it seemed 
that a helpful discussion of the entire subject 
would be read with great interest. Boys 
in high school, preparing for college, want to 
know what subjects to study so they may 
progress as fast as possible; older men, out 
in the whirl of daily existence are eager to 
know what books will help them to get a 
good technical foundation in radio theory; 
and radio salesmen want to learn the tech- 
nical facts about the merchandise they are 
selling. This article does not pretend to 
present complete instructions for success 
for any of these interested persons. But 
there is information here which should be of 
genuine aid. Mr. Henney, who is director 
of the RADIO BROADCAST Laboratory, is a 
graduate of Western Reserve, and of Harvard 
University which granted him the degree of 
Master of Science. THE EDITOR 



perience with radio apparatus. This experi- 
ence should include both transmitting and re- 
ceiving apparatus, and here is where the 
"amateur" has the advantage over his brothers 
who casually decide to enter the radio world. 
It is probable that the greatest number of 
our future radio authorities will come from 
the ranks of these so-called amateurs, youths 
who construct and operate apparatus that 
enables them to converse with other amateurs 
across unbelievable distances. 

It is surprising what an advantage these 
amateurs have when they go to college for 
their further training. They have the "feel" 
of radio equipment, they are already familiar 
with laboratory apparatus, and they have 
acquired first-hand knowledge that gives them 
a great advantage over their classmates. 
These relatively inexperienced men who are 
not so fortunate require some considerable 
time to gain equal familiarity. 

The student should pay as much attention 
to his mathematics and physics as possible 
during high school, for all that is learned here 
will save time in college. If he has time for 
French in high school, 
several years of that 
language will be a 
great help. Or French 
and German may be 
learned in college, and 
if the student has a 
fair reading knowl- 
edge before his arrival 
there he will find it a 
distinct advantage. 
These two languages 
have become impor- 
tant adjuncts to an 
engineer's training, 
for so much good 
work is being done on 
the Continent that a 
well posted expert 
must keep in touch 
with what goes on 
there. One ought to 
follow the work of for- 
eign investigators in 
their own language. 

After arrival in col- 
lege, the student may 
approach radio from 
one of two angles, 
either through the 
conventional elec- 
trical engineering de- 
partment or through 



346 



Radio Broadcast 



the physics department. For the first year 
the courses studied will be much the same 
Whether the student is in engineering school 
or in the "arts" college where he will elect 
scientific subjects. 

A continuation of his higher algebra, trig- 
onometry, analytical geometry and an in- 
troduction to the calculus will complete his 
mathematical background for the more serious 
work to follow. He will go through the usual 
Freshman English which is aimed to give him 
practice in writing. He will continue his 
foreign languages, and probably learn some- 
thing of history, sociology, or economics. 

In the second college year, the student en- 
gineers continue to study more mathematics 
and they begin to branch out and to concen- 
trate in their various fields. Both the engin- 
eers and the physics students learn something 
of the several branches of physics. Electricity 
appeals to the embryo radio expert, but he 
should not forget that acoustics has become a 
very important part of radio engineering, and 
his course on sound will prove valuable in his 
future work. 

The third and fourth years are given to 
more specialized courses. The study of 
vacuum tubes, and their properties of amplify- 
ing, detecting, and oscillating, will be begun, 
and for the radio enthusiast, this course will 
prove to be more than interesting as will the 
study of oscillations and electric waves. 

Should all this time and work seem un- 
necessary to the budding engineer, he should 
remember that he will be forced to compete 
with other engineers, and that the better 
trained will have the better chance of success. 
The attendance at colleges and technical 
schools increases each year, and it seems that 
the youth who passes up a college training 
without good cause will find himself somewhat 
handicapped. 

THE WIDE SWEEP OF RADIO 

RADIO is perhaps the broadest of the 
various related fields of electricity, for 
it requires knowledge and practise derived 
from engineering, from physics, from chemis- 
try, and from mathematics. For this reason, 
the radio man who is being trained for radio, 
should have as broad a scientific education 
as he has time to accumulate. 

The radio engineer must know the funda- 
mentals of electricity, and there is no royal 
road to this knowledge. He must understand 
the principles of the various branches of 
physics, such as light, heat, electricity, me- 
chanics, and sound. He must be able to 



design apparatus that can be made by ordin- 
ary machine practices, for a device that cannot 
be manufactured might as well not be in- 
vented, from a practical point of view. 

All of these subjects require a knowledge of 
mathematics, and the more a man is at home 
with his algebra, and his trigonometry and 
his calculus, the better is he able to visualize 
the electrical and mechanical problems that 
come to him. 

At the present time, there are surprisingly 
few really outstanding radio experts in this 
country. Among them are college professors 
whose training and experience has been so 
extensive not necessarily in engineering 
that they can speak authoritatively on radio 
theory and radio practises. There are others 
whose training has not had the formality of 
any college at all, but they have learned their 
profession in the more arduous one of experi- 
ence. It is probable that none of these men 
hangs out his shingle as a "radio engineer." 
It is probable that few of them can copy 
"twenty words a minute" of Continental 
Morse code. 

A real engineer then, is one who understands 
electricity, who can design apparatus, not 
merely building it by the cut-and-try method, 
and who by the aid of his mathematics can 
arrive at preliminary solutions to important 
problems without the necessity of long labora- 
tory experiment. 

"COMMUNICATION" COURSES 

SOME technical schools are recognizing 
that the field of communication is a dis- 
tinct entity within the larger one of electrical 
engineering. As a result, their communica- 
tion courses include more about vacuum tubes, 
for example, than about power machinery. 
Included in such courses is work on telephone 
lines and their associated apparatus, the 
methods of signalling under water, telegraph, 
and, naturally, radio. 

"MAN SPECIFICATIONS" 

AN INTERESTING statement was made 
some time ago by John Mills, a promin- 
ent educator and engineer who hires the 
technical men for the Western Electric Com- 
pany and indirectly men for the American 
Telephone and Telegraph Company. In this 
statement he said: 

I look for six characteristics, without regard to 
the engineering course in which the student has been 
trained; and I accept for the same opportunity men 
who as arts college students have had no engineering 
courses whatever. 



What Are the Royal Roads to Radio? 



In the first place I look for "intellectual curiosity." 
Unquenched and unquenchable intellectual curiosity 
is to my mind the first requisite for growth in our 
rapidly progressing age. The second requisite is the 
ability to study. It is perhaps the one real aim in 
education. The percentage of population which 
has the ability to study is much less than the per- 
centage of degrees and other evidence of learning 
would indicate. Learning looks to the past, while 
study looks to the future. 

The third requirement is the habit of study. 

The three remaining requirements have nothing 
to do with the content of engineering courses, but 
they have a great deal to do with the natural 




water, but he was curious to know how, and 
to-day his intellectual curiosity has got him 
much farther than his fellows who were not 
particularly thrilled by the fact that"HaO" 
was the chemist's shorthand symbol for one of 
nature's grandest explosions. 

WHAT TRAINING IS VALUABLE 

TT IS surprising when one looks over the 
I names of those who appear in the Who's 
Wlno in Engineering to see the great number of 
prominent men who have had general college 
training and who are, technically speaking, not 
engineers at all. On the other hand one 
should not forget that President Emeritus 
Charles W. Eliot of Harvard University was a 




Ha 



rdCV 



CRUFT HIGH TENSION LABORATORY 

At Harvard University. This building is one of the few university 
buildings in the country devoted exclusively to radio work. The 
oval shows students at work in one of the laboratories. Dr. E. L. 
Chaffee is standing at the extreme left. Most of the students 
who are taking work in this building are graudate students, many 
of them from other universities than Harvard. Professors George W. Pierce, A. E. Kennelly, and Dr. E. 
L. Chaffee give courses and supervise radio research at the Laboratory 



characteristics of the student and his general 
training; they are: first, the ability to learn from 
men; second, the ability to cooperate with men; 
third, a promise of the ability to lead men. 

In connection with the first requirement, 
intellectual curiosity, the writer remembers 
distinctly a fellow student in freshman chemis- 
try. A young instructor was lecturing at 
some length upon the simple fact that two 
molecules of hydrogen and one of oxygen 
combine to form the well known "HaO", and 
this chap wanted to know "how." Such a 
heretical question apparently astonished the 
instructor, for he struck up the usual attitude 
of a young teacher who finds himself in deep 
water. 

But that freshman who was not satisfied by 
knowing that hydrogen and oxygen did form 



professor of chemistry, or that Herbert 
Hoover is a graduate mining engineer. 

It seems that aside from the intrinsic value 
of a technical education, there is much to be 
said in favor of general training. It is prob- 
able that the best-known doctors, lawyers, 
and educators are those who have studied 
many subjects not directly related to their 
particular interest. 

Here again it is "intellectual curiosity" and 
the ability to study that counts, for a man 
trained in one field may find himself thrust into 
another. It is probable that the executive 
engineers who become presidents of corpora- 
tions are those who have had the widest 
possible training outside of their narrow 
technical study. 

Benjamin Franklin was "craftsman and 



348 



Radio Broadcast 



tradesman, philosopher and publicist, states- 
man, patriot, and diplomat." Yet, too, he 
was a scientist. 

Good radio courses are given by many state 
universities, and the work that is done at 
Harvard University under Professors Pierce 
and Chaffee, at Columbia by Professor More- 
croft, and by Professor Hazeltine at Stevens is 
well known. There are a number of technical 
schools like Rensselaer or Massachusetts In- 
stitute of Technology that give highly special- 
ized work in radio subjects in connection with 
their departments of electrical engineering. 

The student who cannot go to one of these 
large institutions should not feel discouraged, 
for any well taught engineering course will 
give him the background for research or gradu- 
ate work in radio subjects. It must be remem- 
bered that a radio engineer may be a physi- 
cist, and there are few colleges that do not have 
physics departments. The principal thing 
for the student to remember is to get the 
fundamentals of electricity and mathematics 
well in hand; the value of the superstructure 
of one's training depends entirely upon how 
well the ground work has been laid. 

COMMERCIAL RADIO SCHOOLS 

THOSE who are interested in radio and who 
cannot go to college can learn a great deal 
about radio. It is probable that the greater 
number of workers in this fascinating study 
fall into this class, for they are those who are 
now working with radio equipment and have 
neither the time nor the inclination to go 
through the somewhat lengthy process of be- 
coming thoroughly trained. 

The point is that any one can be well posted 
on radio, and can become well acquainted 
with radio phenomena at home, or by attend- 
ing some radio school. Before the day of 
broadcasting such schools confined their ac- 
tivities to preparing men for the government 
commercial license examinations. To-day the 
picture has changed and presents a much 
broader aspect. Experts are needed for sales- 
men, for operators, Tor broadcasting duties, for 
inspectors in manufacturing plants, and for 
designers of radio apparatus. Each of these 
particular positions requires somewhat different 
training, but the fundamentals of radio should 
be understood by all. And it is these funda- 
mentals that can be learned at home, or in day 
or night school, or by correspondence. 

The Department of Engineering Extension 
of Pennsylvania State College gives two 
courses by correspondence. One of these is 
an elementary course for those who know little 



about radio; the other is more technical and 
complete in its scope and uses as its text, the 
book Principles Underlying Radio Communi- 
cation prepared by the Bureau of Standards. 
These schools draw their students from all 
walks of life, there are few professions that are 
not enrolled. A statement from one of the 
large radio schools is significant: 

An analysis of last year's enrollment showed 
that 134 distinct and separate professions were rep- 
resented in our student body, and among them 
were doctors, lawyers, electrical, mechanical, and 
civil engineers, postmasters, building contractors, 
dentists and men of similar occupations. 

CHOOSING A RADIO SCHOOL 

THE task of choosing a radio school is no 
simpler than that of choosing a college; 
there are the same questions to be answered. 
One should decide what one is to expect from 
such a school and to find out whether it offers 
the course that is wanted. Some schools are 
offering courses in radio research for the ad- 
vanced student, but there is no reason why the 
enthusiast cannot perform the experiments 
included in such a course at home provided 
he has the apparatus. 

It is surprising how many of the funda- 
mental facts of radio may be discovered by 
reading and by simple measurements that 
any radio hobbyist may do. In future issues 
of RADIO BROADCAST will be found descriptions 
of apparatus and experiments that will teach 
much about the characteristics of tubes used 
as amplifiers, detectors, and generators; of the 
theories of resonance and tuning; of the effects 
of resistance in circuits, and of similar work 
in high frequency alternating current cir- 
cuits. 

Those who have had technical training 
should get acquainted with their mathematics 
again, specially the major operations in alge- 
bra, trigonometry and calculus. They should 
master alternating current theory, especially 
the effect of inductance and capacity in tun- 
ing. Technical articles appearing in the radio 
publications, especially in the Proceedings of 
the Institute of Radio Engineers may be read 
with much profit. Here are descriptions of 
modern radio stations, amateur, ship, broad- 
casting, and high power, complete with techni- 
cal data and methods of operation. Here, too, 
are descriptions of new applications of existing 
apparatus. 

The correspondence and day or night schools 
have much to offer for those who want to know 
more about radio, and the good that can be 
done in this direction is incalculable. Radio 



What Are the Royal Roads to Radio? 



349 



is suffering from a lack 
of first hand informa- 
tion. 

The stores that are 
doing the largest busi- 
ness are those that em- 
ploy trained radio 
salesmen, and it seems 
reasonable to suppose 
that those that will 
continue to exist in 
these days of compe- 
tition will be those that 
are best posted on radio 
facts. The buying pub- 
lic likes to feel that the 
salesmen know what 
they are talking about. 

RADIO BOOKS 

MANY books have 
appeared on radio 
since the advent of 
broadcasting. Some of 
these ^appeal to some 
people, but seem 
sketchy and stupid to 
others. It is impossi- 
ble to recommend a 
book unless one knows 
the background of the 
reader. A book that is 
too technical for some 
is too simple for others; 
and there you are. 

Books are a reservoir 
of knowledge and those 
that are listed below 
are not all that have 
been printed by any 
means. Two that may 
be obtained from the 
Superintendent of Doc- 
uments, Washington, 
D. C., should be part 

of every radio man's library. They are the 
Principles Underlying Radio Communication, 
which costs one dollar, and the Bureau of 
Standards Bulletin No. 74, which costs sixty 
cents. 

Books written for the laymen are Radio 
Communication by E. W. Stone, An Outline of 
Radio by John V. L. Hogan, and Dunlap's 
Radio Manual by Orrin E. Dunlap, Jr. John 
Mills' book Letters of a Radio Engineer to his 
Son presents the fundamentals of radio science 
in an unusual and interesting manner. 

Among the more technical books, there are 




A MARINE RADIO OPERATOR AT WORK 

Senior operator J. T. Williams, and Captain John Roberts of the S. S. Homeric. 
Part of the tube transmitter is visible. Those who want tjo gain as much radio 
experience as possible often spend several years or more as a marine radio 
operator. Operators, when they are granted their government licenses, are 
thoroughly examined on their knowledge of radio theory and practise. Prac- 
tical experience aboard ship is very valuable to the man who wants to have a 
thorough knowledge of radio. Great numbers of prominent radio men have 
graduated from the marine operator class to positions of considerable radio 
success. The amateur radio operator learns much about the fundamentals of 
radio without leaving his own home. He can gain much from a study of good 
radio text books and magazines, and more by practical experiments with 
radio. The study of radio at home, as the author points out in this arti- 
cle, although it cannot substitute for study at a technical school or college, can 
do much toward building a radio groundwork 



none that are as complete and as useful as 
Professor Morecroft's Principles of Radio 
Communication. Thermionic Halves, by Van 
der Bijl is useful to the vacuum tube student, 
but this book is highly technical and was 
written from the point of view of the telephone 
engineer. The mathematically inclined reader 
and those who crave exact proofs of state- 
ments will enjoy Professor Pierce's Electrical 
Waves and Electrical Oscillations which, by the 
way, contains some excellent material on elec- 
tric lines and filters, a subject that is treated 
very sketchily in other publications. 



4$ ike krocldcaster sees xi 

Toy CxcVzl LlxeKear 




Drawings by Franklyn F. Stratford 



High Power and Elimination of Strays 



THE only reason that static is bother- 
some, even occasionally, in radio re- 
ception, is that the amount of energy 
normally picked up from a distant sta- 
tion is almost incredibly minute. Dr. W. R. 
Whitney of the General Electric Company, 
is reported to have calculated recently, that 
the energy expended by a house fly in climbing 
one inch up a wall, is equal to the total energy 
which would be picked up by a one-foot loop 
at Schenectady, New York, from a normal 
broadcasting station in San Francisco, over a 
continuous period of 35 years. Yet we know 
that, given a suitable receiver, reception of 
KGO on a one-foot loop at Schenectady is not 
an extraordinary feat. It is the amplification 
required and available in a good set which 
is extraordinary. 

When amplification is raised to this level, it 
is to be expected that any natural or artificial 
electrical forces which may happen to be hang- 
ing about will also make themselves heard in 
the loud speaker. Leaving aside the relatively 
rare periods of local lightning, static interfer- 
ence is not caused by the strength of the static, 
but by the weakness of the signal. The static 
is not particularly vicious, but we stick our 
hands into its cage, in DX reception, and in- 
vite it to bite us. Or, to change the metaphor, 
we look for needles in a haystack, and then 
complain of the hay. Archimedes said that 
given a long enough lever, and a place at the 
fulcrum to rest it on, he could move the earth. 
The modern radio engineer can paraphrase 
Archimedes with the declaration that, given 
enough stages of r. f. and a. f. amplification, 
he can sit in California and hear all the x-ray 
machines in Maine; or, since we are talking 



about static, he may hear all the lightning 
flashes in Korea and all the meteorites hitting 
the Heaviside layer, assuming that this cosmic 
bombardment gives rise to certain varieties of 
static, as has been alleged by some specialists 
in the subject. 

In discussing static interference in radio it 
is necessary to differentiate between interfer- 
ence with program service and interference 
with distance reception. Static frequently in- 
terferes with distance reception, particularly 
in the summer, because the received signal re- 
quires great amplification. Interference with 
program service is relatively rare. When the 
signal from a given station in a given locality 
is strong enough to ride over the usual disturb- 
ances, this ability being taken as the criterion 
of program service, it will be found that pe- 
riods of abnormal disturbance are not as 
unusual as railroad wrecks or tornadoes, but 
neither are they more common than "rotten" 
pictures at the movies, or automobile tire 
punctures, or arguments with one's wife. In 
other words, as regards static, radio is in the 
position of other public utilities and domestic 
conveniences with reference to their peculiar 
difficulties; it is imperfect, but good, and not 
to be appreciated until one has to do without 
it. 

While we are thus attempting to view the 
problem in its true proportions, it is not to be 
denied that a compact, cheap, simple static 
eliminator would be of great utility, especially 
to people who live several hundred miles from 
the nearest broadcasting station, and of even 
more value to listeners in the tropics, 
where static is at its worst. A nice little tube, 
to be connected in the antenna lead, which 



Higher Power Will Mean Better Broadcasting Service 



351 



would stop the static and let the signals go on 
down, would be just the thing. 1 would go 
to the five -and ten-cent store myself to buy 
one. Unfortunately, while many good men 
have attempted to invent some such device, 
and have brought great ingenuity and assid- 
uity to bear, the job remains to be done. 
Very successful means of static reduction 
have been devised, but all are complicated 
and costly. They are used only in long dis- 
tance radio telegraph circuits, where the plant 
investment is in any event great and where 
profits are more or less proportional to ability 
to ride over static disturbances. Most of 
these successful methods operate on the di- 
rectional principle. The signal comes from 
only one direction, and the static may come 
from a different direction. If you can confine 
your reception within as narrow an angle as 
possible, pointing in the direction of the ap- 
proaching waves of the desired station, you 
may be able to shut out an appreciable propor- 
tion of the static. This is the principle of the 
barrage receivers of Alexanderson, the loop-, 
vertical combinations of Pickard, some of 
Weagant's devices, and the "wave antenna" 
of Beverage, Rice, and Kellogg. The latter 
employs antennas nine miles long for trans- 
oceanic reception. The antenna is supposed 
to be about a wavelength long, so even for 
broadcast reception one needs about a quarter 
of a mile. As yet no one has put up a wave 
antenna on Riverside Drive or Michigan 
Boulevard! In any case, for broadcast recep- 
tion, the direction of all such telescopic 
receivers must be variable, since one will gener- 
ally want to listen to stations in any direction. 
Many aspiring anti-static gladiators come 
forward periodically with vest-pocket elimina- 
tors which do not work, but which add to the 
gayety of the indus- 
try; Recently the 
ancient device of two 
circuits, one tuned to 
the wavelength of the 
desired station, the 
other to some other 
frequency, followed 
by rectification in 
each branch, and an 
a. f. balance in a 
differential trans- 
former, was once 
more revealed. This 
method was in its first 
flush of youth in 
about 1916; it was de- 




aooui 1910:11 was ae- .-. -, . c ,1 n T . . . ,-. -i 

scribed in a paper by "^V hunt lor needles and object to the hajr 



Dr. Cornelis J. DeGroot, "On the Nature and 
Elimination of Strays," (Proc. Institute of 
Radio Engineers, Vol. 5, No. 2, April, 1917.) 
Whosoever is interested can also discover, in 
the printed discussion following the article, 
some of the reasons why this plausible method 
will not work. 

Another exhibit is found in an issue, early 
this year, of a trade paper advertising one of 
those five tube stabilized radio frequency sets, 
with three big knobs and two or three little 
ones, which is an imitation of an imitation of 
a five tube stabilized radio frequency set, but 
no doubt just as good. There is the usual cut, 
with captions on either side detailing the vir- 
tues of the set, and heading all the other claims 
is the bald statement, "It Eliminates Static." 
Of course it doesn't. 

However, although the ordinary broadcast- 
ing receiver is not a static eliminator, it is 
important to note that when improperly used 
it may show a much less favorable signal-to- 
static ratio than when properly handled. The 
output of a vacuum tube is of course a limited 
quantity. If it is pushed too hard, a point is 
reached at which the signal volume can no 
longer be increased, while minor disturbances 
are still swinging the grids over the steep por- 
tion of the curve. This results in bringing up 
static or inductive interference or whatnot, to 
the disadvantage of the desired modulation, 
which is incidentally distorted. Not infre- 
quently one sees receivers which are capable 
of delivering a clear, relatively disturbance- 
free output of moderate volume, pushed to a 
point where a mushy signal, full of squeaks, 
crashes, and hisses, but loud enough to be heard 
in the next county, is duly brought forth. A 
radio receiver of the usual design cannot be 
expected to do the work of a public address 
system, any more 
than a billy-goat can 
drag a five-ton load. 
If more people would 
form the habit of 
holding down the am- 
plification to a com- 
fortable level, com- 
plaints of radio noise 
interference would be 
greatly reduced. 

Finally, freedom 
from static and 
other extraneous 
sounds is a matter of 
transmitting power. 
Given the power, 
we can ride over 



352 



Radio Broadcast 



anything within reason. With inadequate 
power, one is in the position of a man talking 
in a whisper in any crowded place. Radio 
communication is inherently a problem in am- 
plification. In the studio one starts with 
energy of the order of microwatts millionths 
of a watt. This is enormously magnified to 
the level of say 500 watts in the transmitting 
antenna, but the method of distribution is such 
that the receiver gets only a few microwatts to 
work with. Once more this is amplified, until 
it is strong enough to actuate a loud speaker 
reproducing the original sounds. But here is 
the rub: where amplification at the transmitter 
brings up only the desired sounds, as 
amplification at the receiver magnifies these 
and all other impulses that happen to be flying 
around. The former is selective amplification ; 
the latter is general, undiscriminating amplifi- 
cation, except in the one particular of fre- 
quency selection. 

Thus even the engineer who is skeptical 
about static elimination at the receiver, sees 
no reason why static cannot be substantially 
eliminated by perfectly feasible increases of 
power at the transmitter. Largely, in fact, 
this has already been accomplished. People 
who live within a few miles of a powerful sta- 
tion hardly know that static exists. Farther 
out, they hear it occasionally, but it is hardly 
as annoying as the coughing at a symphony 
concert a form of disturbance which, inciden- 
tally, is effectively eliminated for radio lis- 
teners by close microphone placing. With the 
constant increase in power of broadcasting 
stations, the area of practically interference- 




JK) more can a tilly^odt pull A 5 ton load 



free reception increases in proportion. The 
time is not so far off when the area subject, 
more or less, to radio disturbances, will dis- 
appear entirely, just as the frontier of the 
United States disappeared, through the in- 
crease and distribution of the population, 
toward the end of the last century. 

Among the Broadcasters Howard E. 
Campbell 

MR. CAMPBELL was a radio man in the 
days when "broadcasting" was not 
yet in a radio man's vocabulary. He 
is now chief radio engineer and director of 
broadcasting for the Jewett Radio & Phono- 
graph Company of Detroit, which is about to 
put into operation a 5-k. w. station at Pontiac, 
near that city. 

Leaving the University of Indiana in 1909, 
Mr. Campbell enrolled in the Naval Electrical 
School at Brooklyn, New York, where trem- 
bling amateurs and professional aspirants, a 
few years later, were summoned for their oper- 
ator's license examinations, before the Depart- 
ment of Commerce took over that function. 
But that examination Mr. Campbell did not 
take until in 1912, after spending most of the 
intervening period as a Naval Radio Electri- 
cian in Atlantic waters, for the simple reason 
that until 1912 there was no examination to 
take. With his first grade ticket he made one 
trip as a marine operator in the coastwise 
service, before being transferred to the Mar- 
coni Company's installation force early in 
1913. Ultimately he became chief radio in- 
spector at the port of New York for the Mar- 
coni Company, and no doubt held down many 
a key while squeezing the last milliampere out 
of the old quenched spark set. He also in- 
stalled sets on sealing vessels in Newfound- 
land. 

By this time, apparently, Mr. Campbell felt 
that he had graduated from marine radio, for, 
following a brief period as technical assistant 
at the Aldene, New Jersey, plant, he is next 
discovered as engineer-in-charge of the 300- 
k. w. New Brunswick, New Jersey, transatlan- 
tic station, which was a timed-spark outfit of 
the type still being used at Stavanger, Norway 
(LCM), for communication with the United 
States. New Brunswick was under test at 
this time, and soon after that job was in a 
stage of completion Mr. Campbell went out 
to Bolinas, California, to assist in the installa- 
tion of a similar outfit for communication with 
Hawaii and Japan. All this, of course, was 



Strong Radio Signals for Every Farmer's Front Yard 353 



in the dot-aml-dash business; radio telephony 
was still in the incubator. 

In February, 1917, Mr. Campbell was 
engineer-in-charge at Bolinas, and then the 
war came along. The day after the United 
States declared war against Germany, the 
station and all of its personnel were taken over 
by the Navy, Mr. Campbell remaining in 
charge with the rank of Radio Gunner. When 
the armistice was signed he was officer-in- 
charge of the Naval Radio Training School 
at Marshall, California, following which he 
went back to Bolinas, 
as Chief Radio Gunner, 
to recondition the sta- 
tion before it was 
turned back to the 
Marconi Company by 
the Navy. In May, 
1919, Mr. Campbell 
was detailed as Radio 
Communication officer 
on the staff of the 
Pacific Coast Commu- 
nications Superinten- 
dent, and this turned 
out to be his last 
assignment in the ser- 
vice, for in September 
he received his dis- 
charge and returned 
to his home in New 
York City, in plenty 
of time to participate 

in the broadcasting boom which started in 
the East in September, 1921. 

As soon as Mr. Campbell reached New York 
he made a connection with the Western Elec- 
tric Company as radio designing engineer, and 
in that capacity he had much to do with the 
design of the first 5OO-watt radio telegraph and 
telephone transmitter, from which the present 
standard 5Oowatt broadcasting outfit was de- 
veloped with comparatively unimportant mod- 
ifications. Having been in intimate touch 
with the design, Mr. Campbell was ready to 
operate this equipment when he became chief 
engineer of station wwj in Detroit early in 
1922, and his success may be judged by the 
fact that this station was shortly cited by the 
Bureau of Standards as one of the few standard 
frequency stations of the country, varying 
from its assigned frequency less than one-tenth 
of one per cent, over a period of seventeen 
months. From wwj, Mr. Campbell passed 
over to his present connection. 

Mr. Campbell has been a full member of the 
Institute of Radio Engineers since 1914. 




HOWARD E. CAMPBELL 



Radio Is Too Urban 

FROM Miami, Arizona, comes a com- 
ment by Mr. W. H. Mayfield relative 
to the discussion of DX vs. Programs 
in our April issue. Mr. Mayfield points out, 
pertinently enough, that some listeners are DX 
hunters through necessity. "The closest 
station of any size," he writes, "is 450 miles, 
air line, whereas a 45omile circle drawn 
around Mr. Dreher's listening post would un- 
doubtedly include a hundred stations. We 
necessarily have to be 
'DX hounds' here, if 
we are to get anything, 
and to listen to stations 
for selection after selec- 
tion without announce- 
ment, and when the 
announcement is made 
to have it entirely un- 
intelligible, or 'down 
in the trough,' as he 
puts it, is discouraging, 
to say the least." 

Mr. Mayfield sug- 
gests that the an- 
nouncer have a key 
and buzzer handy, and 
give the call signal in 
Continental Morse. 
There are numerous 
objections to this 
method. Here in 

New York only one of the announcers in my 
acquaintance knows the code well enough to 
learn to send even a simple combination of 
letters. Announcers are not chosen for tele- 
graphic ability, but for a ready tongue, a 
pleasant voice, knowledge of music and show- 
manship, good manners and a measure of 
good looks. (The last to put female artists 
into a pleasant frame of mind, so far as possi- 
ble). In the second place, nine-tenths of the 
listeners know as little code as the announcers. 
Thirdly, code signals, almost as much as key 
words like Watch George Yoke, would be out 
of atmosphere. At one station in the East 
there was a device for chopper-modulation of 
the carrier whenever the microphone was off, 
giving a characteristic monotonous note 
of musical pitch for listeners to tune to. It 
sounded pretty nasty on test, and was never 
put on the air. 

The answer to the problem is twofold: 

(i) Frequent announcing with modulation not 
below the mean level of the music. We shall be 
glad to hear from listeners about stations which 



354 



Radio Broadcast 



neglect to give their call letters at reasonably fre- 
quent intervals, it being borne in mind, however, 
that on some types of programs, such as church ser- 
vices and theatrical features, frequent cut-in an- 
nouncements may not be feasible. 

(2) Adequate power to reach the backwoods. 
Radio is at present too much an urban proposition. 
The people out on the plains and up in the hills need 
it as much, and more, and they will buy the sets 
when the service is offered them. One of the kings 
of France Henry was his name, but I don't recol- 
lect his number offhand who had a great zeal for 
the welfare of his subjects, declared his ambition 
was that every French peasant should have a fowl 
in his kitchen pot on Sunday. Well, every Amer- 
ican farmer must have a radio signal field strength 
of I .o millivolt per meter in his front yard on Sunday 
and every other day. When all announcements 
made are certain to reach the listeners, then the 
determination of the proper frequency of call-letter 
repetitions will be a trifling problem indeed. 

Is Government Action Needed on the 
SOS Question? 

ON MARCH 2ist there was another east 
coast sos, and Mr. John S. Dunham, 
of Larchmont, New York, kept a log 
of the proceedings, sending a copy to Mr. 
Arthur Batcheller, United States Supervisor 
of Radio in the second district, and one to us. 
The record is very complete and covers from 
7.46?, when the alarm was first given, to 8.27, 
when NAH (Brooklyn Navy Yard) sent out the 
"Resume traffic" message. 

WEAF apparently got the original sos, or an 
immediate relay, for it is in this instance in 
the honorable position of going off the air 
first, at 7.46. wjz, WNYC, WOR, WGBS, KDKA, 
and others kept right on broadcasting. At 
7.57, NAH, the naval control station in this dis- 
trict, sent out a QRT (Stop Sending). There- 
upon wjz took off its carrier, followed within 
a few"minutes by WNYC, WGBS, and WOR (8.01). 
The inland broadcasters continued their pro- 
grams, and WIP, Philadelphia, 508.2 meters, 
likewise failed to break its carrier, until 8.22, 
when Mr. Dunham's log states, "WIP at last 
off." 

Mr. Batcheller, in a communication to Mr. 
Dunham, commented as follows: 

"Class B stations only, which are on the 
coast and capable of interfering on 600 meters 
are required to cease transmission during the 
transmission of an sos and signals relating 
thereto. Inland Class B stations and all'-Class 
A stations are not required to cease" trans- 
mission." 

That puts the sos situation substantially on 
the basis we advocated in our first article on 



the subject in RADIO BROADCAST. (We do 
not mean to imply that that brought about the 
readjustment, which had probably been in 
contemplation for some time.) 

However, Mr. Dunham feels that all sta- 
tions above 300 meters should cease broad- 
casting when an sos goes out, on the ground 
that damage to antenna or apparatus might 
necessitate the use of a lower wavelength than 
600 meters, the standard distress call wave- 
length. He calls attention, also, to the case of 
WIP, which is Class B, near the coast, and not 
so far from 600 meters. There may be a 
difference of opinion on the first question, and 
evidently the Department of Commerce, hav- 
ing liberalized the rules, considers the low- 
wave distress call contingency remote. But, 
whichever way you look at it, there is little 
to be said in favor of WIF if Mr. Dunham's log 
is correct. 

Dr. Frank W. Elliott, Manager at woe, also 
contributes to this discussion, pointing out 
that the Department of Commerce has never 
seen fit to enforce the regulations as regards 
inland broadcasters, and that it would be 
difficult to pick up sos calls on either coast at 
points in the Central states. He writes fur- 
ther: 

"If some way could be developed to give 
information to the stations inland by telephone 
or telegraph I am sure that all would be willing 
to cooperate. I know that we would." 

It was not our intention to criticise the in- 
land broadcasters in this regard. We were 
calling attention to a general condition, using 
particular stations merely for illustration. 
The fact remains that some of the sos calls 
which take the coast broadcasters off the air 
originate several thousand miles out at sea. 
A powerful inland station on one of the higher 
wavelengths might conceivably interfere with 
the traffic following such a call. The argu- 
ment in the March issue was for a formula or 
some equivalent means of differentiating dan- 
gerous stations from the others. This still 
seems a rational procedure. It is merely one 
of a number of radio problems which could 
stand scientific investigation as a basis for 
appropriate action. 

Receiving equipment exists which could 
give an adequate sos service to those broad- 
casters, however, far from the coast, who 
might be designated to stand an sos watch. 
Or, as Doctor Elliott points out, a wire service 
might be organized. 

We are glad to hear from woe, not only for 
their specific addition to what has been said 
on the sos question, but because the exchang- 



The Progress of a Young Electrician 



355 



ing and debating of different points of view 
among the broadcasters is exactly what this 
department is here for. 

The Memoirs of a Radio Engineer. 
II 

BESIDES constructing an electrophorus, 
from which, when the weather was not 
too wet, sparks could be drawn, my 
companions and I built several detecting de- 
vices, or electroscopes. These were of two 
general types, which used metal foil and pith 
balls, respectively. The latter form consists 
very simply of two small sheets of gold-leaf or 
other very thin metal foil, suspended from a 
metal rod so that they will separate on the 
approach of an electric charge, owing to the 
repulsion effect between two similarly charged 
bodies. In our case, we stuck a fairly heavy 
copper wire through the cork of a pickle bottle, 
or any bottle of diameter uniform over the 
entire length, bent it over at the lower end, 
and hung pieces of aluminum foil over the 
horizontal part of the wire. The object of the 
bottle was to shield the apparatus from air cur- 
rents. The proud operator of the electroscope 
would demonstrate it, before a gaping congre- 
gation of children, by running an ebonite 
comb, very likely stolen, through his hair, 
and bringing it close to the upper end of the 
metal rod or wire. Promptly the leaves would 
separate, standing stiffly apart at an angle of 
about forty-five degrees. For a small consid- 
eration, the spectators were permitted to rub 
the comb, each in his own hair, and by per- 
forming the experiment personally to satisfy 
themselves that there was no fraud. Many 
of them believed that the electricity was 
drawn out of the head, that some individuals 
had more than others, and that there was a 
peculiar virtue in having a great deal; argu- 
ments arose as to who had the most, and in 
the more acute cases led to fist-fights and 
neighborhood feuds. One boy in particular 
vaunted himself on his remarkable virility, 
for he was able to make the pieces of foil leap 
apart so violently that they reached the sides 
of the bottle and clung there. His enemies 
maintained, probably not without truth, that 
he was able to do this because his mother never 
made him wash his head. They caught one 
of the stray cats of the neighbourhood, rubbed 
its back with the comb, and proved that it 
yielded an even more striking effect on the 
electroscope than the hair of the champion, 
who stood near by, surrounded by his adher- 
ents, sneering. Finally one of them threw a 



rock, smashing the electroscope; the cat es- 
caped, all the contestants, abandoning science, 
rushed to arms, and in the ensuing melee 
I received a bloody nose, neither the first 
nor last injury of that nature which I 
sustained. 

The other type of electroscope worked on 
the same principle, but utilized pith balls 
suspended by threads. The pith we obtained 
by hunting for the dried stalks of weeds, which 
abounded in the vacant lots of the Bronx. 
Pith ball electroscopes were cheaper, and hence 
more common. One could be bought from the 
manufacturers, if I recollect, for about five 
marbles of the type known as "immies," while 
the aluminum foil product sold only for cash. 
As much as ten cents changed hands in some 
transactions. 

These experiments were successful and 
profitable, but many other adventures in static 
electricity failed. For example, we were never 
able to build a static machine, or generator of 
static electricity with moving parts. Our 
greatest ambition was to own what is known as 
a Wimshurst machine, which consists of two 
glass disks revolving in opposite directions, 
with brushes and combs for drawing off a 
continuous charge. This was beyond our con- 
structional ability, and we had no more chance 
of buying one, with the money derived from 
snow shovelling, running errands, and begging 
from our parents, than we had of buying a rail- 
road or an automobile. Yet we yearned for 
one, hopelessly and yet pleasurably, as a farm- 
hand longs for a Follies girl or a case of Scotch. 
Always there is something beyond one's reach, 
and one must accept substitutes. We tried to 
build a simpler electric machine, using a re- 
volving glass cylinder rubbing against a silk 
pad, and we did succeed in mounting a bottle 



roved, "fliat {here was no fraud 




356 



Radio Broadcast 



on a shaft turned by a crank, but no amount of 
turning and sweating got us an appreciable 
static charge, presumably because the glass 
was not the right kind. We fell back on the 
electrophorus as a generator. 

Another great diversion was collecting or 
accumulating charges in condensers, which 
were known to us only in the form of Leyden 
jars. These we manufactured out of glass 
test tubes, coated on the outside with tinfoil, 
and filled with salt water for the inside elec- 
trode. By imparting about fifty charges from 
the electroscope to the ball of the Leyden jar, 
one could get a fairly severe shock on 
discharging the jar. This was far more enter- 
taining than the comparatively feeble, pain- 
less, and less noisy sparks of the electrophorus. 
The spark of the Leyden jar was blue and loud, 
and by combining a number of test tubes one 
could get it to jump as much as a quarter of 
an inch. We persuaded one innocent youth 
to hold such a battery in his hand, and to 
present his tongue to the brass ball which was 
connected to the inner coating; the shock 
knocked him down, and in falling he broke the 
four condensers of the battery. Thus we were 
justly punished for our cruelty. 

This incident marked the limit of our prog- 
ress in electrostatics. We now turned to 
experiments with electric currents, as distin- 
guished from static charges, and numerous 
galvanoscopes and galvanometers devices for 
detecting and measuring electric currents 
were built and torn apart. Our raw material 
was mainly in the form of old electric bells, 
which we bought from the neighborhood 
electricians for ten cents apiece. Some of 
them had been incapacitated by a coat of 
kitchen paint, others concealed a dead cock- 
roach in their vitals, many had simply failed 
from old age, but they were all precious to us 
for the two electromagnets which they con- 
tained. Some of these we unwound from the 
core and rewound on cardboard forms, within 
which a magnetized sewing needle, suitably 
suspended, twitched violently when a dry 
battery was connected to the terminals of the 
coil. We attached scales to these instruments, 
but we had nd means of calibrating them and 
so they never really measured anything. 
However, 1 do recollect building a tangent 
galvanometer, on which I worked for some 
months, the frame consisted of one of those 
small wooden hoops which are used in em- 
broidering, which I got from my sister, by 
either force or stealth. The scale was cor- 
rectly laid out, and probably the instrument 
was capable of fairly accurate measurements, 



but at the time I built it I did not know what 
a tangent was nor what part it played in the 
operation of the galvanometer. 

Our great problem was a source of current 
supply, for when our dry cells ran down we 
frequently had no money with which to buy 
new ones. A dry cell cost a quarter, equiva- 
lent to five strawberry frappes or the same 
number of visits to the nickelodeon, as the then 
primitive movie theatres were called. Some- 
times we were able to get more or less ex- 
hausted cells, from garages or electricians, at 
a much reduced rate, and various householders 
in the neighborhood, sympathizing with our 
endeavors, gave us their warn-out batteries. 
These we attempted to rejuvenate with in- 
jections of vinegar, salt water, and on one 
occasion I was inspired to try beer (5 per cent, 
alcohol in 1909) but the improvement was 
not worth the beer. 

And now, at the age of about thirteen, we 
became telegraphers. Our communication 
was neither by radio nor over a wire, for at 
first we had only one instrument, which was 
communally owned and operated. The key 
and sounder were separate, and constructed 
mainly of wood, with a few screws and wires 
for the current-carrying and sounding parts. 
For example, the lever and the anvil of the 
sounder were both of wood, whittled from a 
cigar box, but screws were provided at the 
proper points in order to obtain the proper 
clicking sound. The sounder magnets were 
taken from a bell, of course, and likewise the 
armature. The difficulty of learning the 
Morse code dampened the ardor of all except 
some four of the group of urchins who had 
originally started out to become electricians. 
There was no drama in sitting in a cellar and 
making stupid clicking noises for hour on hour. 
We were considered to be obsessed by a dull 
and malignant spirit, and in fact we did go 
around telegraphing to each other by mouth 
signals of the dah-dit-dah variety, and many 
people took us for idiots incapable of intelligi- 
ble speech. Even in school we practised in 
solitude by clicking pencils between our teeth 
or portions of the desks. Occasionally we 
would go down to a near-by railroad station 
and hang around the ticket office, listening to 
the sounders of the railroad telegraph, but the 
speed was much too great for us and we only 
caught a letter now and then. We looked with 
envy at the station master and wondered if 
we should ever own a real telegraph sounder 
of shiny brass, mounted in a mahogany reson- 
ator, with a tin tobacco can jammed between 
the anvil and the wood to give each sounder a 



When "th" Gets on the Air 



357 



characteristic tone. As yet all we were able 
to get was the tobacco can. 

It was not long before we were able to secure 
a few hundred feet of annunciator wire, and to 
build additional wooden keys and sounders, 
enabling us to connect our several homes and 
to spend our evenings telegraphing instead of 
doing our lessons. By that time we were good 
for about 12 words a minute in American 
Morse, with its spaced characters. Conti- 
nental Morse, save perhaps in cable traffic, 
was not yet recognized in the United States. 
Even radio, in this country, started in Amer- 
ican Morse and continued so for several years. 
As yet we were not interested in radio. We 
were aware that such a thing existed 
"wireless," it was called, but no one knew 
anything definite about it. It was unknown, 
remote, nebulous, no doubt costly; we regarded 
it somewhat as a grocer thinks of celestial 
mechanics not very pertinent to the practical 
business in hand. 

(To Be Continued) 

I I 

| Microphone Miscellany j 






"Irate Listener" 



ON MARCH i4th, early in the evening, 
wj'z in New York was rebroadcasting 
a concert from 2LO, London, the stuff 
going from the Savoy to 5\x, Chelmsford, by 
wire line, thence over the Atlantic on 1,600 
meters, to be picked up at the Radio Corpora- 
tion experimental station at Belfast, Maine, 
retransmitted on 112 meters, picked up again 
at the laboratories adjacent to Van Cortlandt 
Park, New York, amplified, and sent down to 
/Eolian Hall on 42nd Street by wire line, 
where finally it modulated its last carrier and 
could be heard by any one within range of 
wjz. 

While the congratulatory telegrams were 
pouring in, a listener called up on the tele- 
phone, gave his name, and with unrestrained 
indignation spoke his mind, as follows: 

"I listen to your station often and enjoy 
your programs . . . but your quality 
seems different. It isn't my set, other stations 
sound all right. There must be something the 
matter with your microphone. Why don't 
your engineers get on the job? Don't they 
know what they're sending out?" 

Finally the studio attendant who had an- 
swered the telephone managed to get in a 
word, a great light burst on the complaining 



BCL, and with a single Oh! he hung up the 
receiver. 

THINGS I AM TIRED OF ON THE RADIO 

WIOLET ray machines. 
Hearing middle aged sopranos coyly 
singing "The Lilac Tree," and, worse, seeing 
them do it. 

Publicity stunts in which some self-styled 
musical genius broadcasts on 200 watts to his 
loving wife and children seated at the receiver 
in Tibet, 8,000 miles away. 

Radio critics who turn out stuff like this: 

Nature, in a mjelting mood last night, was not 
generous to radio. Languorous air made thick the 
voices of soprano and barytone and injected squeaks 




We 



Around. iKe ieledrapli office 



into the tender violin. Though they brightened as 
the night waxed cooler, the effects were most lugu- 
brious early in the evening. 

THOSE ELUSIVE TH's 

THE best broadcasting station in the 
world, and the finest receiving set and 
loudspeaker, can't as yet reproduce the conso- 
nant combination tb to perfection. Thus 
when the announcer of a New York station, 
broadcasting from the annual radio show and 
convention at the Hotel Pennsylvania, told 
the radio audience, "The grand ballroom is all 
filled with booths, that innocent word came out 
on the air as boo^e, an altogether unintended 
indictment or compliment. 

EVERYBODY BELIEVES IT, BUT IT'S NOT SO 

COMEBODY probably Artemus Ward 
**? said that it isn't the things we don't 
know that hurt us, but the things we know 
that aren't so. A few examples in the radio 
art: 

That a coupled circuit receiver cannot radiate. 



358 



Radio Broadcast 




at tteir detut all ariists are panicky 

That broadcasting stations have a decrement. 

That generators in a broadcast transmitter always 
result in a noisy carrier and that the only remedy is 
to buy a bank of storage batteries. 

That artists appearing before the microphone for 
the first time are all in a very panicky state and 
about ready to faint with fright. 

COMFORT FOR THE ANNOUNCERS 

CVERYBODY, including myself, takes 
J ' pleasure in harassing the announcers for 
their lapses, mistakes in diction, and whatnot, 
in spite of the knowledge that they have to 
make up what they say as they go along, 
admittedly no easy task. One would think, 
sometimes, that only announcers make mis- 
takes. To disprove that theory, may we not 
present the first sentence of an announcement 
sent out by the wealthy and influential New 
York section of a national electrical organi- 
zation 

"There has been procured for our next meet- 
ing two speakers of prominence in the en- 
gineering and business world, who will 
talk. . . ." 

Have the stenographer of the honorable 
secretary of the section no knowledge of Eng- 



lish grammar? Have she no proof-reader? 
Have . . ." 

What About a Broadcasters' 
Association? 

IN THE United States and Canada there 
are about 600 broadcasting stations, with 
staffs numbering from one person up to 
sixty. Probably the average personnel is 
around four. That would make a total of 
about 2400 professional broadcasters. 

There were not that many radio engineers in 
the world when the Institute of Radio Engi- 
neers was founded in 1912, and that was 
antedated by five years by the venerable So- 
ciety of Wireless Telegraph Engineers. The 
technicians among the broadcasters are largely 
affiliated and those who are not, should be 
with the Institute of Radio Engineers. But 
broadcasting, after all, is a special occupation, 
and it is probable that before long the broad- 
casters, both program officials and technical 
men, will feel the need for some form of 
association of their own. In two or three or 
five years broadcasting will have got over its 
growing pains, and the energy for founding 
such a body will become available. Some of 
the owners of broadcasting stations already 
have an organization, but what we are think- 
ing of is an association of the men who actually 
book the programs, make the announcements, 
and turn the knobs, and whoever may be in- 
terested in their work. 

In the meantime, our hope is that this 
department of RADIO BROADCAST will serve as a 
broadcasters' forum, where all the practition- 
ers and friends of the art will have a chance, 
not only to watch the general flux of projects 
and ideas, but also to express thoughts, contri- 
bute opinions, and to vent feelings which, in the 
present adolescence of the industry, frequently 
require such relief. 



AN EFFICIENT RECEIVER FOR SHORT WAVES 



of the best known experimenters in the country, George j. Eltz, jr., 
is developing a receiver for use on very short waves. The circuit errr 
ploys super-regeneration a highly efficient" receiving method on the very 
high frequencies. Broadcast listeners who want to hear the short wave 
broadcasting now taking place at several large American stations, and trans- 
mitting amateurs will find Mr. Eltz' receiver an excellent addition to their 
equipment. It will be described in an early number 



How to Be a Good Radio 
Neighbor 

PART ONE: WHY YOUR RECEIVER SQUEALS 

Helpful and Informative Discussion by Two Radio Authorities on the 
Menace of Squealing Receivers How to Tell What Receivers Oscillate into 
the Antenna and How to Prevent that Oscillation Practical Instruction on 
How to Operate Your Receiver Without Annoying Your Radio Neighbors 

BY JOHN V. L. HOGAN 

Consulting Radio Engineer 



GENERALLY speaking, there are 
two types of whistling interference 
heard in radio receivers. One 
type is the result of two broad- 
casting stations sending simultaneously at 
wave frequencies (wavelengths) that are too 
close together. Their waves react on each 
other and produce a more or less uniform 
whistling note, often of very high pitch, in all 
the radio receivers within range. This sort 
of interference is somewhat bothersome when 
listening-in on the present thickly populated 
broadcast wave bands It is daily growing of 
less importance, and for the moment we need 
not consider it further, although it will be dis- 
cussed in a future article of this series. 

The second type of whistling interference is 
caused by radiating receivers, or, in other 
words, by receiving stations that are so 
designed and so operated that they act as 
small radio transmitters. This kind of inter- 
ference is exceedingly troublesome and breaks 




FIG. I 

The old time single-circuit regenerative receiver 
which is the worst offender where radiation is con- 
cerned. When in an oscillating condition this 
circuit is a very effective transmitter 



up a great deal of broadcast reception. It is 
particularly a nuisance in localities where there 
are many radio receivers close together, as in 
the cities; but even in the country this squeal- 
ing and whistling interference often prevents 
satisfactory receiving. 

It is safe to say that nearly every broadcast 
listener has heard the chirp or whistle of rapidly 
varying pitch that is the mark of this kind of 




FIG. 2 

The variocoupler-variometer circuit also is a gener- 
ator of squeals. When in an extremely sensitive 
oscillating condition it possesses the ability to pass 
energy into the antenna circuit which creates in- 
terference in neighboring receivers 



interference. Many listeners, however, do not 
know what causes the troublesome whistles 
and many do not know that their own receivers 
may be adding somewhat to the nightly din 
of squawks and squeals. 

WHY WHISTLES OCCUR 

THE reason for these chirps and whistles is 
not known to many radio listeners, al- 
though the scientific basis of the action is not 
complicated. It is merely another mani- 



360 



Radio Broadcast 




^\AA 

i t ~^~ ^ 

H- jf. 



THE INCORRECT WAY 

Of connecting a variocoupler. Here the coupler is connected to a detector circuit with the rotor coil 
used as a tickler to produce regeneration. While this circuit is more sensitive than the one illustrated be- 
low, it is quite broad in tuning and is an excellent transmitter of squeals 



festation of the common phenomenon of 
"beats" that is frequently noted in acoustics. 
You may have observed that when two musical 
tones of neighboring pitch are sounded simul- 
taneously, the combined tone flutters in in- 
tensity. This happens because the two sound- 
waves interact or "beat" together, and the 



rapidity, of the flutter is always equal to the 
difference in frequency of the two sounds. 
Thus, if two organ pipes of 32 and 36 vibrations 
per second, respectively, are blown at the same 
time, the sound heard will grow strong and 
weak (or flutter in strength) four times per 
second. 




THE CORRECT WAY 

A standard variocoupler consisting of a primary and secondary winding connected to the other essentials 
of the circuit in a way that will not cause the outlawed radiation. Tuning is accomplished by the vari- 
able condenser and the switch making contact with the switch points indicated 



How to Be a Good Radio Neighbor 



361 




FIG. 3 

The threc'circuit tuner consists of primary, second- 
ary, and tickler coils. Radiation may be somewhat 
diminished by employing a primary coil having 
only a few turns, loosely coupled to the secondary 



In the same way, if two radio waves or two 
radio frequency currents of somewhat different 
frequencies are allowed to interact upon each 
other they will produce beats. Thus a carrier 
wave from station WEAF, at the frequency of 
610,000 cycles per second, might interact with 
the carrier wave from another transmitter 
at 611,000 cycles per second to produce 1000 
beats per second. When picked up and recti- 
fied, such beating waves would produce, in the 
listening telephones or loud speaker, a note of 
1000 per second pitch, corresponding approxi- 
mately to the second C above middle C on the 
musical scale. Any change in frequency of 
either beating wave would produce a change in 
the pitch of the beat note, since this must al- 
ways equal the difference in the two wave 
frequencies. 

In the same way, a carrier wave from any 
broadcasting station will beat with waves or 
currents produced by any self-oscillating re- 
ceiving set. The frequency of the oscillations 




in the receiver, and of the waves that those 
oscillations will send out if they are allowed 
to get into the receiving antenna, depends 
upon the tuning adjustments of the receiving 
set. As the tuning knobs are turned, the 
frequency changes. Consequently the pitch 
of the beat-note produced also changes, and 
this is what gives rise to the bird-like chirps 
and whistles that are so often heard. 

If you have a radio receiver of any of the 
types that can be made to cause oscillations 
in the antenna circuit, your set is one that may 
interfere with your radio neighbor's reception. 
The receivers that can be made to generate 
antenna circuit oscillations, and thus to inter- 
fere with receiving throughout the neighbor- 
hood, are probably made and used in larger 




FIG. 4 

A blocking tube circuit which was fully described in 
the March and May, 1924, issues of RADIO BROADCAST 



FIG. 5 

Is the recent circuit contribution to radio by Roy A. 
Weagant. A description of the additional ap- 
paratus and its method of use is contained in the text 



numbers than the non-radiating and hence 
non-interfering sets. 

TYPES OF RADIATING RECEIVERS 

NEARLY, if not absolutely, all of the inter- 
ference-producing receivers 'are of the 
simple regenerative type, though more com- 
plicated outfits such as the super-heterodyne, 
when used with an antenna, may cause this 
trouble. They may be of single-circuit 
double circuit, triple-circuit or of any other 
design; the offending set may be of the unneu- 
tralized radio-frequency amplifier or reflex 
type. Many of these will generate oscillations 
in the antenna circuit and produce interfer- 
ence if not specifically designed otherwise, 
particularly when they are not correctly 
handled by the user. 

There are only two ways to stop the whist- 
ling interference produced by oscillating re- 
ceivers. The first and simplest way is simply 



362 



Radio Broadcast 




RADIO BROADCAST Photograph 
A THREE-CIRCUIT TUNER 

Which illustrates very well the method of obtaining very loose coupling between primary and secondary 
to reduce the possibilities of radiation. The parts are labelled respectively T, tickler, S, secondary, and 

P, primary 



to tune and manipulate your own receiver 
properly, and to teach your radio friends to 
do the same with theirs. A little work among 
your near-by radio listeners will produce 
wonderful results, for no one wants to trouble 
his friends. Ordinarily, by a little coopera- 
tion, a neighborhood can be relieved of 
the strongest receiver-produced whistles quite 
easily. The second and more difficult method 
is to arrange your receiver so that it cannot 
produce oscillations, or so that when it does 
oscillate, the currents will not reach the an- 
tenna. By preventing the generation of 
oscillations in your antenna you prevent the 
radiation of interfering waves. 

IS MY RECEIVER OSCILLATING? 

MANY of you are perhaps wondering how 
you can tell whether or not your own 
receiver is ever a source of neighborhood inter- 
ference. There is one simple rule that answers 
this question: //, when turning your wavelength 
or tuning control knob, you hear a whistling note 
in your telephone or loud speaker and if, also, 
you can change the pitch of that note by turning 
the tuning knob, you are making interference for 
all the listeners who live near you, unless your 



receiver is so designed that it will keep the oscilla- 
tions out of the antenna circuit. Whistles 
whose pitch you cannot control do not come 
from your set, and you need not blame your- 
self for causing them. On the other hand, if 
you have no blocking tube in your set, when- 
ever you, hear a whistle and find that you can 
vary its pitch by moving your tuning control, 
you may be sure that all your neighbors who 
are listening to the same station are hearing 
the same whistle. Thus you are not only 
spoiling your own reception but also theirs. 

Unless you use a blocking tube, the wise and 
considerate thing to do is to keep your receiver 
adjusted so that it is not in an oscillating con- 
dition. Whenever you hear a whistle of this 
kind, stop your set from oscillating. If you 
will follow that rule and will impress its im- 
portance upon your radio friends, you will 
find that great reductions in the amount of 
whistling interference can be made. 

The article which follows, by Dr. A. N. Gold- 
smith, gives a detailed description of how to tune 
without permitting your receiver to radiate 
and so show you how to protect your neigh- 
bors from interference caused by the oscilla- 
tions of your set. 



How to Be a Good Radio Neighbor 

PART TWO 
Operating Your Radiating Receiver Without Squeals 

BY DR. ALFRED N. GOLDSMITH 

Chief Broadcast Engineer, Radio Corporation of America 



363 



EVERY time your receiver produces a 
squeal in your own telephones or loud 
speaker, or every time it is in what is 
called the "oscillating condition," you are 
spoiling your neighbor's enjoyment of his con- 
cert and annoying people who have done you 
no harm. (There is but one exception to this 
rule, and that is the new non-radiating regener- 
ative and non-radiating super-heterodyne re- 
ceiver, which is specially built at the factory 
so that it will not radiate appreciably when 
used in accordance with the manufacturer's 
instructions. The definite "non-radiating 
guarantee" of a reputable manufacturer re- 
lieves the user of worry relative to this point). 
May I make an earnest plea to you, to apply 
the best possible rule of conduct, and to do 
to other broadcast listeners only what you 
would like them to do to you? Would you 
like to be interrupted by a loud noise while 
you were listening to a beautiful selection on 
the fine receiver which you bought or built 



recently, and which represents toil and ex- 
pense? Would you want an evening's party 
ruined, after your guests had assembled to 
hear a particular concert which they were en- 
joying, by some inconsiderate outsider who, 
instead of being a good neighbor, is really a 
neighborhood nuisance? Surely you would 
not want either of these things. Then re- 
member that it is up to you to consider other 
people. 

HOW TO TUNE YOUR RECEIVER 

BUT," you may rightly ask, "how am I 
to avoid bothering my neighbor? What 
must I do? No one has yet given me definite 




RADIO BROADCAST Photograph 
THE INCORRECT WAY OF TUNING 

A regenerative receiver. Rotating the tickler or regenerative dial causes bird-like tweets to be radiated 
from your antenna. The effect on the neighbors is well known 



364 



Radio Broadcast 



instructions." And it is to give you a partial 
answer to your proper and reasonable ques- 
tions that this article is written. In it, a few 
simple rules are set forth, which, if consistently 
followed, will make your neighborhood cleaner 
and quieter in the radio sense, and enable you 
and everyone else to be reasonably sure of an 
evening's entertainment whenever you want 
it by radio. Of course, the best and simplest 
way is to use a guaranteed non-radiating re- 
ceiver. The following rules apply, however, 
to receivers which can radiate. 

1. Find out what adjustment, or adjust- 
ments, on your set make it oscillate. By this 
I mean, turn the knobs of your set experi- 
mentally until you find that knob (or those 
knobs) which, as you turn them past a cer- 
tain point, cause the well known squeal or 
tweeting birdlike sound in your telephones or 
loud speaker. Usually this knob is labeled 
Tickler, or Amplification, or Volume Control, 
or Loud-Soft or some such term. In some sets 
it is even marked Potentiometer. In other 
sets, there will be several knobs which cause 
the trouble of squeals, including the filament 
current control knob. 

In all this, I assume that you are not using 
an ordinary super-heterodyne or super-regener- 
ative set on an antenna. If you are, all I can 
say is, please don't. Put that set on a loop 
right away. If it does not work on a loop, it 
is so badly designed and built that it had best 
be replaced by some other set. Any one who 
deliberately uses a set which is continually 
oscillating like the'ordinary super-heterodyne 
or super-regenerative sets on an antenna, is 
either ignorant of what he is doing or devoid 
of consideration for his neighbor. In the 
radio sense, he is a public nuisance. 

Assuming, then, that you have found the 
knobs which cause your set to squeal, try to 
carry out the next suggestion. 

2. a) Get a clear idea of the settings of each 
of these knobs where the squealing begins, for 
the stations to which you generally listen. 

b) Then mark with a pencil the point on 
the scale of each knob where the trouble be- 



c) To make it still clearer, a small piece of 
white paper may be pasted next to the scale 
with its left hand edge at the point marked by 
the pencil. 

d) The pencil or paper mark on the scale 
then represents the danger mark. Whenever 
you approach it, you are coming nearer and 
nearer to making trouble for others, and you 
should proceed with the utmost caution in so 
doing. (There are some sets for which this 



plan will not work because the settings of the 
knobs are too complicated and too variable. 
But it will work particularly well for many 
of the simpler sets.) 

3. In using your receiver, develop the habit 
of slowing up the knob-turning process as you 
get near the danger mark. There are people 
who twist the Tickler knob around until they 
are sure that the set will produce squeals, and 
then they throw the wavelength control knobs 
for selecting a station, back and forth rapidly, 
thus producing a multitude of howls in other 
people's receivers. This is a vicious way of 
picking up a station. If such people knew 
what their neighbors thought of them, they 
would be astonished. Why store up ill will 
and discourage other people in their attempts 
to listen? Don't do it, but give them a chance 
by picking up only such stations as you can 
get WITHOUT HAVING THE KNOBS IN 
THE POSITION WHERE SQUEALS CAN 
BE PRODUCED. I know that this means 
very careful work in handling the set at times, 
particularly for receiving other than local sta- 
tions, but it is truly worth while. Get into 
the habit, and you will be astonished how easy 
it will soon become. 

4. If you have the kind of a set which pro- 
duces squeals (and too many people have), 
be content with a little less distance rather 
than making so much trouble in the air. If 
getting a very remote station means a great 
deal of fussing and adjustment and a lot of 
squeals, you had better let it go, and listen to 
nearer stations. You will be a neighborhood 
blessing if you do. 

INSTRUCTIONS FOR NEIGHBORLY RADIO 

TO PUT it differently, don't overwork your 
set. Keep away from burning the fila- 
ments of the tubes too brightly or increasing the 
plate battery voltage or altering the set con- 
struction as received from the factory, or doing 
any of the other things which may possibly 
give a little more distance, but, on the other 
hand, make you a pest. If you have a re- 
ceiver which does not radiate (and there 
are some excellent varieties now on the 
market), leave its construction severely alone. 
It left the factory in proper shape and if you 
meddle with it, you are bound sooner or later 
to put it out of order. 

It is hoped that there is not too much of the 
sermon in this article. But it is so simple a 
matter to avoid producing squeals that refus- 
ing to take the slight trouble necessary to 
avoid them is.likethrowing banana peels on the 
sidewalk. It may be a natural and thoughtless 



How to Be a Good Radio Neighbor 



365 



act, but the man whose leg is broken when he 
slips and falls, knows that you have been 
guilty of criminal carelessness. The person 
who produces radio interference deliberately 
is not only violating the law of the land but is 
also devoid of the spirit of community help- 
fulness. Broadcast listeners of the United 
States, give an extra minute and a little 
thought to your neighbors when tuning your 
set, and urge them to do the same for you. 



THE WEAGANT RADIATION ELIMINATOR 

Early this year Roy A. Weagant, Chief 
Engineer of the Deforest Radio Company, re- 
leased to the public the circuit diagram 
showing the use of a small choke coil and con- 
denser in regenerative receivers for eliminating 
radiation. The circuit is that of Fig 5. The 
heavy lines show where these two pieces of 
apparatus are inserted in such a circuit. The 
usual antenna circuit consisting of the antenna, 
primary coil, and ground is not employed, the 
antenna coil being eliminated with the antenna 
connected to the grid of the audio-frequency 
tube and the ground connected to the negative 
side of the A battery. 



The theory of operation as explained by the 
Deforest Company is as follows: 

It will be seen from the circuit that the in- 
coming signal is impressed upon the grid of 
the audio-frequency tube instead of the grid 
of the detector tube. This audio-frequency 
stage acts as a radio-frequency amplifier re- 
sulting in radio-frequency variations in its 
plate circuit. The insertion of the choke coil 
L2 produces a radio-frequency potential which 
is passed to the grid of the detector tube 
through the condenser C. Inasmuch as this 
condenser has a small value of capacity and 
the grid and plate capacity of an audio- 
frequency is very small, any oscillation of the 
detector tube causes only a negligible amount 
of radio-frequency current to be passed into 
the antenna. The capacity of condenser C 
is .000025 mfds. and the choke coil has a very 
high inductance. It is composed of many 
small coils connected in series. Each coil 
has a natural wavelength some place in the 
broadcast wavelength. THE EDITOR 




RADIO BROADCAST Photograph 
THE CORRECT WAY OF TUNING 

A regenerative receiver. Here, the tickler dial is turned nearly to zero. The tuning is mainly accom- 
plished with the condenser dial, the first one on the left. Once a station has been received, the regenera- 
tive dial may be advanced, but not beyond the point where squeals are produced. In some receivers, the 
left dial is the tickler and the right the antenna tuning dial. A glance inside the cabinet will usually 

make this point clear 



liiiiiiiiiiiiiimiiiiiiiiiiiiiinii 



For the Radio Beginner 

How to Make a Radio Receiver for $1.82 



IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIH 



E WHO have played and worked at radio for many years are perhaps 
prone to neglect the thousands that every month approach their first 
radio experiments. Beginners are apt to be discouraged by the complexities 
which are life and nourishment to the average fan, and to which, as a popular 
radio magazine, we have given the most attention. We have, however, pub- 
lished an occasional article for the less advanced enthusiast, and the reception 
which has been tendered them, has encouraged us to inaugurate a department, 
devoted to the education and interest of the radio beginner. He will find here 
articles on the construction of simple apparatus built from inexpensive -ma- 
terial. Particular attention will be paid to the possibilities of five-and- 
ten-cent store parts. 

The editor will he pleased to hear from readers to whom this department 
is dedicated, telling him what they would like to see in it, the problems they 
would like discussed, and the sets they wish to build. We shall gladly con- 
sider manuscripts and short notes dealing with the design and construction 
of simple apparatus and shall pay for acceptable material at our usual rates. 

THE EDITOR. 



RADIO to-day is neither an expensive 
nor a complicated proposition, unless 
the enthusiast himself desires to make 
it so. The advent of the five-and-ten- 
cent store into the radio field has cut the cost 
of almost all parts, and these, arranged into 
simple circuits, present the logical start for 
the radio beginner's first experiment. 

The crystal receiver we are describing was 
constructed entirely of such items. They 
can be duplicated in almost any of the five- 
and-ten-cent stores scattered throughout the 
United States and Canada, for one dollar and 
eighty-two cents. 

THE PARTS FOR THE CRYSTAL RECEIVER 

'IPHE parts used in the construction of this 
* receiver are photographed before assem- 
bly in Fig. i. 

No. i Eleven plate variable condenser, * 

built up of parts; totalling : . $0.77 

No. 2 Dial .10 

No. 3 Crystal detector stand 10 

No. 4 Fixed condenser, .001 mfd. capacity .10 
No. 5 Crystal for detector (shown in 

detector stand) .25 

No. 6 Lightning arrester .10 

No. 7 Switch lever with knob and bushing .10 

No. 8 Four binding posts .10 



No. 9 Winding form cut from pasteboard 
No. 10 Spool of No. 24 enameled wire . .10 
No. ii Switch taps (3 for jc.) .... .10 
Cigar Box 

Total . . . . $1.82 

The lettering beside some of the parts, 
indicates the abbreviation by which they are 
designated on the diagram Fig. 2. 

Extra equipment, if not on hand, may be 
added to the above list as follows: 

Antenna Wire 

Insulators . 

Telephone receivers 

This brings the grand total for complete re- 
ceiving equipment to $5.52. 

If it is desired, a panel and cabinet can be 
substituted for the cigar box. This adds 
considerably to the cost. The writer preferred 
the box arrangement because it simplified con- 
struction, both in the drilling or working of the 
panel material and in the elimination of more 
or less elaborate fittings.- The cigar box can 
be stained if desired, but when merely cleaned 
and sand-papered, it presents a not unpleasing 
appearance. 

Following the accumulation of the parts, 
it is weir to make sure that the necessary tools 



P -40 

.30 

3.00 



How to Make a Radio Receiver for $1.82 



367 



are on hand. While this simple set can be 
constructed with no other implements than 

A pair of scissors, 
A jack-knife, 
A screw-driver, and 
A gimlet 

a neater and quicker job can be made if these 
elementary tools are supplemented by 

A brace, 

A J" drill, 

Countersink, 

No. 18 drill, 

No. 27 drill, 

Hand-drill, 

Reamer, 

A pair of wire-cutting pliers and 

A compass or dividers 

THE PANEL 

THE cigar box should be of average size 
about eight or nine inches long, five inches 
high and two and one half inches deep. The 
paper can be removed by soaking in hot water 
for one half hour. It should be sand-papered, 
dried, and sand-papered again. The hinged 



top of the box is discarded, unless it is attached 
with metal hinges. 

Fig. 3 shows how the "panel" or bottom 
of the box is drilled to receive the mounted 
parts. A horizontal pencil line is drawn across 
the box half way between top and bottom of 
the panel. On the left hand side, a vertical 
line -is drawn 2^ inches in. This line will 
cross the horizontal line at A, at which point 
a quarter-inch hole is bored to pass the variable 
condenser shaft. The screw holes for the 
condenser are drilled according to the pattern 
or "template" furnished with the condenser, 
and are countersunk. 

Two and one quarter inches from the other 
end of the panel, a second perpendicular line 
is drawn. Holes for the detector, the exact 
placing of which will vary with different 
obtainable detectors, are drilled on the upper 
part of this line. The switch lever and tap 
holes are located on the lower portion of this 
line as shown. The tap holes are drilled 
with the No. 27 drill, and the lever hole, B, 
with the quarter-inch size and thus reamed 
to fit the bushing. The radius of the taps 



LA 




FIG. I 

These parts, which altogether cost $1.82, can be built into a simple but efficient receiver. 
All parts, excepting the lightning arrester, item 6, are included in the receiver proper 



3 68 



Radio Broadcast 



N 


y Antenna 




Detector 
. 1% 


r ! 





#*- 




00 ,_ 


O.L 






II 


O 

^-.,25 Turns 

O 


y 






/ 








O15 Turns 








^^1 in Tnrnc *- 






Phones 




Ground 

FIG. 2 

How the different parts of the receiver are con- 
nected. The heavy wire in the antenna circuit 
should not be smaller than No. 14 

will be determined by the length of the switch 
arm. 

Each end of the box is drilled according to 
the right hand sketch in Fig. 3. These holes 
are for the binding posts. 

Care should be exercised in drilling the box 
in order to avoid splitting. The metal drills 
are much preferred to the gimlet. The drills 
should be sharp and turned rapidly but with 
little pressure. This procedure will result in 
clean, unchipped holes. 

After the required holes are drilled, the 
pencil lines should be erased by sandpapering 



and a coat or two of stain can be applied if 
desired. 

THE COIL 

WHILE the stain is drying or perhaps 
while the paper is being soaked from the 
box the coil can be wound. If the builder 
prefers, the winding form can be bought for a 
few pennies from the same ten-cent store that 
supplied the rest of the parts. But it is easily 
cut from stiff card-board in exact duplication 
of the drawing in Fig. 4. It is wound with 45 
turns of wire, over three, under three, with taps 
taken with yth, i4th, and 2ist turns. Over 
three under three means over three spokes of 
the spider-web form, and under three spokes, as 
illustrated in Fig. 5. The turns are wound 
tightly. After seven turns are wound, a loop 
about three inches long is twisted forming a 
double lead. This constitutes the first tap. 
The winding is continued, additional taps 
being made, as directed, at the I4th, and 2ist 
turns. 

In connecting the set, looking at the panel 
from the rear, the start or lower terminal of 
the coil leads to the first switch point (from 
left to right), the ist tap to the second switch 
point, the and tap to the third switch point 
and the 3rd tap to the four or right hand point. 
The outer end of the coil leads to the antenna 
post. Loops are made in the tap leads, and 
the enamel scraped off, so that contact will be 
made with the nuts on the switch points under 
which they are placed. 

Fig. 6 shows how the taps are twisted and 
connected to the switch points. 




r 



^ 



Holes For 
Condenser 



_4. 



Holes'For 
Binding Posts 



BOTTOM OF BOX 



EACH END OF BOX 



FIG. 3 

How the holes should be drilled. The condenser and switch point holeJ are most easily 
Two binding-post holes are 'drilled in each -end of the box 



" Panel layout." 

placed with a pair of dividers or a compass. 



Wiring the Set 



369 



<- Wire 



FIG. 5 

The meaning of 

winding "over 

three, under 

three" 



MOUNTING 

A FTER the eleven plate 
"^ ** condenser has been 

assembled (in many cases 
it can be bought complete 
for the total cost of its 
parts), it is mounted on the 
L panel by the three screws 

i provided for this purpose. 

If the holes in the panel 
' are not quite properly 

spaced, they can be reamed 

slightly to compensate for 
any discrepancy. The dial 
! is adjusted so that zero is 

J at the top of the panel (at 

L which point an indicating 

line may be inked in) when 
-_ Snokes the rotary plates are en- 
tirely out. 

The bushing for the 
switch lever and the four 
switch points are secured 
in their proper places. The 
crystal detector 
stand is mounted 
with a single 
screw through 
the center, two small 
holes on the right hand 
side being provided for 
the leads. 

The remaining parts 
of the receiver, the fixed 
condenser and the coil, 
are supported by the 
wiring in back of the 
panel. 

WIRING THE SET 

THE internal connec- 
tions of the set are 
shown in the diagram 
Fig. 2. Small "a" is 
the antenna post (upper 
left from the front) run- 
ning to the top of coil L, 
to one side of the con- 
denser, and to the crys- 
tal detector. The lower 
terminal and taps of the 
coil are connected as de- 
scribed. The bushing 
of the switch lever is 
wired to the ground post 
-"b" (lower left) and to 
the variable condenser 



and telephone receiver post (lower right) "d". 
The upper telephone post runs to the crystal 
detector. The fixed condenser, C2, is con- 
nected across the phone binding posts, "c" 
and "d." Figs. 7 and 8 are rear and front 
views of the completed receiver. The connec- 
tions within the set may be made with what 
wire is left over after winding the coil. The 
writer, however, had some No. 18 bell or 
annunciator wire, which, being larger and 
stiffer, was a bit better for this purpose. 
Using the parts photographed and described, 
no soldering was necessary. 

THE telephone receivers are connected to 
the posts provided for them. The 
antenna is connected to "a" and the ground 
to "b." The lightning arrester, LA, is con- 
nected between antenna and ground as shown. 
The lightning arrester is conveniently mounted 
on the windowsill. The antenna wire should 
not be smaller than No. 14 B & S gauge, or its 
equivalent in stranded wire, and this same 
large wire should be used for the heavy leads 
shown in Fig. 2. 




3 ^"Overall Diam. 



FIG. 

A pattern for the coil form. 



. . r This may be cut out and 

pasted on cardboard so that it can be duplicated exactly 



370 



Radio Broadcast 



FIG. 6 

Showing the twisted leads or 

" taps," and the manner in which 

they are connected to the switch 

points 




WHAT ANTENNA TO USE 



THE crystal receiver will operate on an 
indoor antenna, but will give much more 
satisfactory results on an outdoor system. 



RADIO BROADCAST Photograph 



For an indoor antenna, it is advisable to 
run a single stretch of wire through rooms 
and hall as far as possible without doubling 
back upon itself. No particular precautions 
need be taken for insulation, nor is a 




RADIO BROADCAST Photograph 
FIG. 7 
Rear view of the crystal set. No soldering has been necessary in connecting the different parts 



The Lead-in, Antenna, and The Ground 



37* 



lightning arrester necessary with an indoor 
antenna. 

A horizontal length of about seventy-five 
feet is best with an outdoor system. A 
longer antenna, while increasing volume and 
distance, generally boosts up interference in 
the same proportion. The antenna should be 
swung as high and clear as is conveniently 
possible. Low antennas and antennas sur- 
rounded by houses and trees will work, but 
efficiency will increase almost in proportion 
with the height and the absence of near-by 
dumbwaiter shafts, tin roofs, trees, and other 
absorbing obstructions. 

The antenna should be insulated at each 
end, and, if possible, the horizontal and 
vertical (which means the lead-in) parts 
should be one long piece of wire, as suggested 
in Fig. 9. It two lengths of wire are used, 
they should be soldered at the joint. As a 
rule more than one wire for receiving is un- 
necessary. 

The lead-in should be guyed away from 
walls if necessary, and should be heavily 
taped or otherwise insulated wherever it comes 
in contact with fire escapes, windows, etc. 
Remember, the crystal receiver depends 
altogether upon the energy the antenna 
system picks up, and it must be conserved 
by every practical care. There is no radio 




gnB i' 

' 



FIG. 9 

A simple but efficient antenna system. If con- 
veniently possible, the stretch A, B, C should be a 
single length of wire 

frequency amplification, or local batteries, 
and the telephone receivers are actuated by 
the minute currents induced by the radio 
wave. 

The lead-in may be brought through the 
top of the window with the usual precaution 
of taping. Or, any of the several lead-in 
devices may be employed if the experimenter 
so desires. 




FIG. 8 



RADIO BROADCAST Photograph 



The complete receiver, connected to antenna and ground, and 
ready for action. No batteries of any kind are necessary or desirable 



372 



Radio Broadcast 




Bind 



FIG. IO 



The layout of the studs or nails, and the 
method of winding the simple low loss coils 



THE GROUND 

THE water-pipe or radiator make equally 
satisfactory grounds. The wire need only 
be wrapped tightly around a scraped portion of 
the pipe and taped. Such a ground, however, 
should be renewed every six months or so. A 
more permanent ground is secured by soldering 
or by using the common ground clamp. A 
ground wire can often be clamped under a 
valve nut on the radiator, forming a lasting 
and satisfactory connection. 

HOW TO OPERATE THE RECEIVER 

THE operation of even a simple receiver is 
a matter best taught by individual ex- 
perience. A good starting point on our 
crystal receiver is to set the switch on the 
second tap, and tune for stations with the 
condenser while the detector is being adjusted. 



The process of adjusting the detector consists 
of moving the catwhisker lightly over the 
surface until a sensitive spot is found. It is a 
simple matter on most crystals obtainable 
to-day where the entire surface is compara- 
tively sensitive. An occasionally difficult 
adjustment can be expedited by having some- 
one ring the doorbell while the catwhisker 
is being moved. A rough buzz will be heard 
in the 'phones when a sensitive spot is dis- 
covered. 

The highest waves will be tuned-in with the 
switch lever set on the right, the lowest waves 
on the left and the intermediate lengths in 
between. 

HOW FAR CAN I HEAR ON A CRYSTAL? 

THE probable range of broadcast receiving 
apparatus is little more than a matter of 
guess. It depends too much on individual 
conditions. Crystal sets have received dis- 
tances over a thousand miles on many occa- 
sions. Using a short indoor antenna, stations 
fifteen miles away have been enjoyably re- 
ceived in our New York laboratory. Using 
an average outside antenna, the crystal set 
as we have described it should not be de- 
pended on for consistent reception of pleasur- 
able loudness over distances in excess of 25 
miles. 

HOW TO MAKE A SIMPLE LOW-LOSS 
COIL 

THE trouble with most low-loss coils, 
from the amateur's point of view, is 
the difficulty in executing the generally 
eccentric windings. The Lorenz, or basket- 
weave coil is an exception to the rule, and it is 
probably more easy to wind than the straight 
solenoid. Like most low-loss coils at broad- 
cast frequencies, losses are lowered, not so 
much by the type of winding itself but by the 




RADIO BROADCAST Photograph 



FIG. I I 

The winding form and three Lorenz type coils. The left 
hand coil has been mounted on a standard honeycomb base 



How to Make Low- Loss Coils 



373 



fact that the inductance (coil) is self-support- 
ing. This eliminates much of the metal and 
insulating supports with their attendant in- 
efficiencies and mechanical problems. Com- 
bined with the simplicity of construction, 
this added desirability recommends the 
Lorenz coil to the inexperienced experi- 
menter. 

A piece of scrap board and a handful of two 
or three inch nails represent the winding equip- 
ment. The heads should be cut from the 
nails. A circle the size of the desired coil is 
circumscribed on the board, and an odd number 
of nails driven into equally spaced points on 
the circumference. The arrangement of the 
points is best laid out with a protractor and 
dividers. Fifteen nails were used by the 
writer, which represents a spacing of 24 
degrees of arc. Twenty four degrees are 
measured from the diameter with the protrac- 
tor, and the same distance (A, B, in Fig. 10) 
is marked off on the circumference with divi- 
ders or compass. 

The length of the nails is governed by the 
height of the contemplated coil and they 
should be driven firmly into the board. 

The manner of winding is illustrated by the 
sketch, Fig. 10. Two turns are placed around 
the starting nail, and the winding commenced 
over one under one. The desired number of 
turns is wound and the coil completed by 
winding the wire twice about the finishing pin, 
which is one nail farther on than the starting 
pin. The coil is laced or bound before it is 
lifted from the nails. Thread is generally used 
for this purpose, tying in four places beginning 
with the crossing between the start and finish 
pins. The coil can be pried up with a knife 
or screw-driver sufficiently to pass the binding 
thread under the inductance. The black 
thread binding can be discerned on the left 
hand coil in Fig. n, in which is shown the 
simple winding machinery and three of its 
products. 

The Lorenz coils can be mounted in a 
variety of simple ways. The left hand coil 
in Fig. 1 1 has been soldered to the terminals 
of the standard honeycomb coil base. A more 
general form of mounting is to clamp the coils 
between strips of wood or bakelite as suggested 
in Fig. 12. 




RADIO BROADCAST Photograph 
FIG. 12 

A simple way of mounting Lorenz coils is to clamp 
them between two strips of wood or bakelite 

Primary and secondary coils can be wound 
alongside of each other as is occasionally 
done in the case of solenoids. It is a good 
idea, however, to overlap two turns in order 
to insure strength in the unit. The secondary 
should be started two turns before the com- 
pletion of the primary. After one turn of the 
secondary, the next to the last turn of the 
primary is wound over the secondary turn. 
The second turn of the secondary is next made 
over the primary turn and the last turn of the 
the primary over the second turn of the secon- 
dary. The secondary is then continued by 
itself. The two coils are so interlocked that 
their self-supporting quality is not weakened, 
However, little is ever gained electrically 
by the winding of primaries in low-loss fashion. 

Low-loss secondaries for broadcast wave- 
lengths can be wound, of course, on various 
diameters. On a three-inch diameter, fifty 
turns should be wound and on a four-inch 
diameter, thirty turns. Shunted by a .0025 
mfd. variable condenser, such coils will cover 
the broadcast band. If the reader desires, 
the inductance for the simple receiver com- 
pletely desscribed on another page of this 
Department can be wound Lorenz fashion in 
preference to the spider-web. Either of the 
two coils just suggested can be wound, and 
taps taken at f , %, and \ the total number of 
turns. 




, HAT Oui 
Readei 
Write Us 




Line Voltages Supplied by Power 
Companies 

THE following letter was received the 
other day from the Brooklyn Edison 
Company, Incorporated, taking issue with a 
statement, in an article by Phil Fay, "Select- 
ing a B-Battery Eliminator," which appeared 
in the March issue of this magazine. 

Editor, RADIO BROADCAST, 

Doubleday, Page & Company, 

Garden City, New York. 
SIR, 

The first paragraph at the top of page 858 of your 
March 1925 issue, states that there are wide varia- 
tions in voltage at different hours of the day and 
night on power circuits ranging between 100 and 120 
volts. We believe this statement, as a definite 
statement, as made in your magazine, is incorrect 
and does electric supply companies an injustice. 

While it is true that in some cases such a variation 
as you mention may take place on lines of some 
companies occasionally, it is not the usual practice 
and we believe that the statement would have been 
more correct if it had been stated that a variation 
in the amount of the proportions given may oc- 
casionally occur. The practice of this company is 
to permit a voltage variation of 4 volts either above 
or below the normal voltage of 120 volts which we 
supply. In other words, the range in voltage we 
undertake to supply is from 1 16 to 124 volts. 

I hope that you will be able to make some correc- 
tion of the statement referred to above in your 
magazine. 

Very truly yours, 

R. A. Paine, Jr. 
Outside Plant Engineer 

E 

The paragraph referred to above is 
i follows: 

"There are many differences between one power 
circuit and another. First, there are wide variations 
in voltage at different hours of the day and night, 
ranging between 100 and 120 volts. These are not 
noticeable in the brilliancy of electric lights or in 
the operation of ordinary household equipment, 
largely because this apparatus, unlike radio equip- 
ment, is not especially sensitive to voltage varia- 
tions of this amount. In a current tap supplying 
a set line, voltage differences are of the utmost im- 
portance." 



What Do the Roberts Knockout Users 
Think? 

THE list of radio constructors all over the 
United States, Canada, and foreign 
countries who have written enthusiastic let- 
ters about their experience with the Roberts 
Knockout Receiver would fill many lines of 
type indeed. There have been a number of 
these correspondents who wanted to get in 
touch with others in their own vicinity to talk 
about their mutual experiences with the cir- 
cuit and to discuss their various experiments 
with it. Keith Henney's article "Progressive 
Experiment With the Roberts Circuit" which 
appeared in RADIO BROADCAST for April, 1925, 
in especial excited a great deal of interest. 
"Can't you put me in touch with other radio 
fans in my city who have been experimenting 
with this remarkable circuit?" was the ques- 
tion we received in more than one letter after 
that article appeared. As a matter of fact, 
similar requests, differently phrased, have 
come in the offices ever since the publication 
of the original article about this circuit by Doc- 
tor Roberts in the April, 1924, RADIO BROAD- 
CAST. The suggestion in the letter printed 
below is therefore not new, but it expresses 
very concisely what a lot of correspondents 
have been suggesting. RADIO BROADCAST 
will publish a list by cities and states of 
the names and addresses of Roberts Knockout 
users providing those users who are interested 
in taking up the suggestion outlined below will 
send us their names and addresses. 

Editor, RADIO BROADCAST, 

Doubleday, Page & Company, 

Garden City, New York. 
SIR, 

About a month ago 1 wrote a letter to Mr. Zeh 
Bouck, partly personal and partly asking some ad- 
vice regarding some trouble I was having with 
a Roberts Four-tube set I had built. I had 
hardly mailed my letter when the April num- 
ber of the magazine came and informed me that 
Mr. Bouck was away on a vacation. The purpose of 



What Our Readers Write Us 



375 



this note is to have you, if you please, tell Mr. 
Bouck when he returns that I have since been able 
to settle my difficulties quite satisfactorily by chang- 
ing the tubes. I wonder if this suggestion is any 
good? Let RADIO BROADCAST offer to print the 
names of some fans in each of the large cities who 
have built say two or three Roberts outfits and are 
willing to share their experiences with others. 
The Roberts circuit is so good that unless you treat 
it right in construction, you'll have trouble. A few 
dont's from one who has done only to his sorrow, may 
save perplexities later on. This is offered for what 
you think it worth. 

Very sincerely yours, 
(Rev.) Robert E. Holland, S. J. 

What Doctor Pickard Thinks About 
Fading 

THERE have been many interesting argu- 
ments presented of late upon the effect of 
weather conditions upon radio transmission. 
Doctor Pickard, Consulting Engineer of the 
Wireless Apparatus Company of Boston, has 
made an intensive study of fading in trans- 
mission extending over a period of several 
years and which has brought out much valu- 
able information. His most important work 
probably has been his study of the eclipse of 
the sun in January, 1925. His observations 
during the period of the eclipse were reviewed 
in a paper which was read before the Insti- 
tute of Radio Engineers in April, and dealt 
rather conclusively with this very interesting 
subject. 

Doctor Pickard's reaction to Professor 
Van Cleef's article, which appeared in RADIO 
BROADCAST for May, is therefore, of especial 
interest. Mr. Van Cleef reviewed in his 
article the factors which influenced the trans- 
mission and reception of radio waves. There 
have been many theories put forth to explain 
the peculiar condition of fading. The most 
popular theory is, perhaps, that of the Heavi- 
side Layer, which, in part, assumes that the 
various ionized layers of the upper atmosphere 
refract, absorb, or aid the waves in their 
passage. Doctor Pickard's letter follows: 

Editor, RADIO BROADCAST, 

Doubleday, Page & Company, 

Garden City, New York. 
SIR, 

I am indeed indebted to you for the galley-proof 
of Professor Van Cleef's interesting article. We 
certainly need the aid of the meteorologist in the 
correlation of weather and radio transmission. 

Few radio engineers who have specialized on 
transmission phenomena still retain the original or 
reflecting Heaviside Layer hypothesis. Not only 
did this hypothesis involve a grotesque amount 



and arrangement of atmospheric ionization, but 
to-day we realize that to act upon waves by con- 
ductivity would damp them out more rapidly than 
it would bend them. It is therefore refreshing 
to find a writer who pays no attention to the 
Heaviside Layer. 

For nearly a quarter of a century it has been 
recognized that those happenings below the isother- 
mal layer, which we call weather, were related to 
radio transmission. Some five or six years ago a 
Frenchman, whose name has temporarily escaped 
me, made a very similar analysis to that of Professor 
Van Cleef, although he came to somewhat different 
conclusions. 

However, I do not share the author's assurance 
that reception conditions can be forecast with the 
same degree of accuracy as the weather, because I 
know several other factors profoundly affect trans- 
mission. But there is little that I can criticize in 
Professor Van Cleef's article. 

The principal factor in radio reception is not the 
electric field at the receiving point, because this can 
be discounted by increased amplification. The 
principal factor, is, however, the height of the dis- 
turbance level or noise background. The fact that 
winter reception is better than summer reception 
is really due to two things. First, there is less 
static or noise background, and second, there is 
less sunlight, and therefore less ionization of the 
lower levels of the atmosphere. 

Sincerely yours, 
GREENLEAF PICKARD. 

On Our Anniversary 

IT IS a pleasure to receive letters of the sort 
reproduced below. Such expressions make 
us feel that our earnest endeavors to present 
to the radio public a magazine of the highest 
grade have not been wasted. But our efforts 
for the last three years have not been confined 
to the dissemination of the best in radio alone. 
In November, 1923, RADIO BROADCAST in- 
augurated the first International Broadcast 
tests. The tests were repeated in 1924 as they 
will be in 1925, and the data obtained from 
these tests as well as in many other and differ- 
ent researches conducted by RADIO BROAD- 
CAST has been invaluable to the radio field. 
Mr. Rice is Manager of Broadcasting for the 
General Electric Company. 

GENERAL ELECTRIC COMPANY 

Editor, RADIO BROADCAST, 

Doubleday, Page & Company, 

Garden City, New York. 
SIR, 

In looking over the May issue of RADIO BROAD- 
CAST I find that it is an anniversary number. I 
congratulate you on the high grade and interesting 
magazine which you have edited for the past three 
years. 

Very truly yours, 

MARTIN P. RICE. 
Manager of Broadcasting. 




Front view of the super-autodyne receiver, assembled on a standard 7 x 18 x j-inch bakelite panel. The 

knob at the lower left is the wavelength change switch which controls the loop. The designation letters in 

this Figure coincide with those in the list of parts, and in the remainder of the illustrations 

The Super- Autodyne 

Complete Data for Building an Improved Type of "Super- 
Autodyne" Using But Six Tubes for Portable or Home Use 

BY McMURDO SILVER 



THE super-heterodyne described in this article has a number of features which 
commend it to the radio constructor. In the first place, it uses six tubes, 
with a total plate current consumption of 12 milliamperes. As for actual mechani- 
cal arrangement and layout, we feel that the author has done a very good bit of de- 
sign, for the set is exceptionally easy to wire, and if the constructional outline is 
carefully followed there should be no difficulties from this source. The entire re- 
ceiver has been concentrated in a 7 x i8-inch panel, a vastly more compact arrange- 
ment than one finds with most super-heterodynes. No reflexing is used. The quality 
of tone we believe excellent. It is somewhat difficult to tune this receiver, as the dial 
functions differ from those in the common types of super-heterodyne. The in- 
terested constructor will, however, find that this is not merely "another super- 
heterodyne." Many radio enthusiasts, old and new, are looking for a portable loop 
receiver to use in vacation trips this summer; this receiver should satisfy their summer 
requirements as well as giving them a set for all-around home use. THE EDITOR 



THAT it possess features which defi- 
nitely lift it above the class of the best 
receivers heretofore developed is the 
first requirement of any new receiving 
system in order that it may, in a measure, 
justify that age-old human cry of "something 
new under the sun." And if for purposes of 
differentiation it is elected to call this new re- 
ceiver by a name which includes the word 



"dyne," then there must certainly be some- 
thing to recommend it other than that its 
designer has managed to unearth some new 
prefix or suffix for that word. The receiver to 
be described in this paper has but two basic 
claims to thefirst of these requirements and one 
to the second it uses but six tubes, and its name 
is as logical as that of the super-heterodyne. 
Essentially, the receiver is a super- 



The Super-Autodyne 



377 



heterodyne, employing an autodyne detector- 
oscillator, and what the writer believes to be 
an exceptionally efficient intermediate am- 
plifier. Because of the use of the autodyne 
frequency-changer, the circuit has been called 
a "super-autodyne," which seems to be a 
more logical name than "super-heterodyne." 
It might be argued that the usual interpreta- 
tion of the word "heterodyne" implies the 
use of a separate detector and oscillator to 
produce a beat note, whereas in this system 
but one tube is used (autodyne). The name 
at least serves to distinguish this system from 
the conventional ones. 

THEORY OF THE AUTODYNE CIRCUIT 

/ T"*HE autodyne circuit, which is the most 
1 interesting feature, is worthy of explana- 
tion. The difficulty which has heretofore 
prevented the use of one tube for both detector 
and oscillator has been that of isolating the 
loop or pickup circuit from the local oscillator 
circuit. It has been impossible to couple a 
tuned pickup circuit to a tuned oscillator 
when the two are to operate but fifty or sixty 
kilocycles apart throughout the broadcast 
wavelength range, and not have the tuning of 
one section react on that of the other. Arm- 
strong and Houck developed the second har- 
monic system, whereby the oscillator, working 
at double the desired wave, did not react 
greatly upon the loop circuit. Then, a 
harmonic of the oscillator was used for hetero- 



dyning. This meant two waves of sufficient 
power to cause radiation were being produced 
by the oscillator, which necessitated the use of 
a muffler tube ahead of the detector-oscillator 
to prevent radiation. Thus, two tubes were 
still used, though the gain in signal strength 
was equal to or slightly better than that ob- 
tained with a good regenerative detector and 
oscillator. At best, this system is not entirely 
satisfactory for home assembly. 

Then came the development of the balanced 
autodyne circuit, by J. H. Pressley, a Signal 
Corps engineer, which performs the required 
function with one tube. 

The actual first tube circuit is shown in 
Fig. 9. The coils L2, Lj ace theoretically 
equal, as are the condensers CX, CX. Actually 
they cannot be made fixed and equal, so CX, 
CX are made adjustable, to obtain substan- 
tially a condition of equality. These units 
make up a bridge circuit, shown by the heavy 
lines. Since L2 equals L^, the potential 
across them is equal, so that it is also equal 
between points 3, and 4, and 5 and 6. Like- 
wise, the potential across CX and CX is equal. 
Since the potential across 3 and 6 is the same 
for both inductance and capacity, then point 
4, 5 and the connection between CX, CX are 
at equal potential, and are also theoretically 
at zero potential, since these points are neutral 
with respect to 3 and 6. Then, circuit Bi, 
C2, 82, may be connected at these neutral 
points with substantially no reaction on the 

V2, VI 




c- 



FIG. 2 



RADIO BROADCAST Photograph 



The completed receiver from the rear. Note how the color cable runs into the assembly, and how two of its 

leads terminate on the rear left posts of transformers Ti and T2. Condensers 9, and Cio should be 

fastened to the under side of the sub-panel, using holes provided in this socket-panel 



Radio Broadcast 




RADIO BROADCAST Photograph 
FIG. 3 

Details of the finished receiver from above. Note how the five leads of the color cable separate: one to tV, 

rheostat R3, one to the switch Si, two to Ti, and one to T2. The gang-socket used in this particular model 

of the set is a home-assembly, and the springs are held by screws. In the factory product, the springs at. 

held by hollow rivets which permit connections to be made from either above or below quite simply 



frequency of the bridge circuit. Further, 
as these points are neutral with respect to 3 
and 6, no energy in the bridge circuit can get 
into Bi, 2, 62, since there is no potential 
difference across these" points of the bridge. 
Therefore, the frequency adjustment of the 
bridge circuit cannot react upon that of the 
Bi, C2, 62, circuit, and vice versa. 



LoctateCondenserspO Here 

/ _ . ^**/^* , \ 



Since the signal is fed from the loop and its 
tuning condenser to the oscillator, it will 
divide equally across the bridge arms. If a 
tube detector is connected across one capacity 
CX, the drop in potential may be used to 
cause rectification. The coil Li, coupled to 
L.2, I_3, causes the bridge circuit to oscillate 
at a frequency determined by these coils, 



c- 




R5 



RADIO BROADCAST Photograph 



FIG. 4 

Bottom view. Condensers C6, Cg, and Cio should be fastened to the sub-panel at the points shown 
similarly to 3, 04 and 5. The proper hole locations are given in Fig. 7. Connections from C3 and G* 
to the socket grid terminals are by means of lugs, just visible between the condensers and the nuts to the real 
This view shows quite clearly how the bypass condensers are held by the same screws holding th< 

mounting brackets 



left. 



The Super-Autodyne 



379 



CX, CX, and Ci which Is made variable for 
the purpose of tuning the oscillator circuit. 
As previously explained, this energy cannot 
get into the loop circuit, so radiation is con- 
fined to what may be experienced from the 
oscillator coil system itself a negligible 
amount. 

It is desirable that the losses in these cir- 
cuits be kept low, particularly in Ci, C2, CX 
and CX. Further, CX and CX should be 
quite small so as not to lessen the tuning range 
of the circuits, and in order that maximum 
voltage may be impressed upon the detector 
terminals. In some cases, it has been found 
possible to use the tube capacity for one con- 
denser CX, while a very small variable was 
used for the other capacity. 

INTERMEDIATE AMPLIFIER 

THE intermediate amplifier is the only 
other unusual feature of the receiver. 
It employs but two stages and is on the order 



ot those described by the writer in RADIO 
BROADCAST for October 1924, and January, 
1925. It differs, however, in that it employs 
transformers which are a compromise between 
the extreme selectivity of properly designed 
air-core coils, and the great stability and am- 
plification of good iron core transformers. 
But two core laminations are used in each 
transformer, of y-mil silicon steel, one in the 
shape of an-'"F" and one an "L". 

CONSTRUCTION OF THE SET 

THE material required to build this re- 
ceiver is listed below, with the designation 
letters used in the diagrams and cuts following 
the quantity of each item required. It is 
entirely permissible to substitute any other 
standard parts for those listed. The actual 
space available is such that if in some instances 
parts of larger or different dimensions are 
substituted, considerable difficulty will be 
encountered in making the units fit in the 




RADIO BROADCAST Photograph 



FIG. 5 

The receiver in an automobile. The A battery supply comes from the automobile by using the Lynch 
Lead. The rather dilapidated bag in the rear holds the B and audio amplifier C batteries. The Am- 
plion loud speaker and the folding loop also go in this bag when not in use. Blanket-roll straps provide a 

convenient means for carrying the set itself 



380 



Radio Broadcast 



up 

a. 

in 


an 

fj| 


space provided. In the case of the r. f. 
transformers, it would be inadvisable to sub- 
^ stitute, since the results of the receiver depend 
.?!,.. in a large measure upon the use of the types 


// H + 




\^P~ 






re 

2 ( 


:ommended. 

Zi, C2 S-M 30I-A (or 3O5-A S. L. F.) Con- 
densers 
4" Moulded dials, vernier type pref- 
erably 
r^ +"S i R4 U. S. L. 6 ohm 


JiMM> 






Wffi^ 


^% 


2 

^^m 


r ^ 




* * 


Y^TT 


<M o ^^o= rheostat 

^ Oil "1 l R 3 U ' ^' L ' 24 
i 00 ^ o u ohm potentio- 


JlflJ&fl?/- 




O^ m meter 
Q!^ o 3 Bi. 62. B^ Insulated top 


i i 
^ 




"^ , c binding posts 


TftOOO^ 




DC 


(i-spring) 
i J i Carter IO2-A 
jack (,3-spring) 
iC-5, 211 S-M 211 filter with matched 
tuning capacity 
2 210, 210 S-M 210 charted intermediate 
transformers 
i Li, L2, L3 S-M loi-B coupling unit 
i S-M or Benjamin 6 gang socket 
shelf (536-20IA, No. 537-199) 
2 Ti, T2 Thordarson 3^:1 or 2:1 trans- 
formers 
2 C?, C8 S-M or Dubilier .5 mfd. Con- 
densers 


s 

CVJoL 

ro 

C\I 


p|: 




CO 

lf^- ^ \+ 






JlQMy- 







OOOOOf- 


2 C3-C4 Muter .00025 mfd. condensers 
with 2 clips 
2 Cg, Cio Muter .002 mfd. condensers 
i C6 Muter .0075 mfd. condenser 
2 CX, CX Continental .000025 m W. con- 
densers 
i Ri S-M or Muter .5 Meg. leak 
i R2 S-M or Muter 2 meg. leak 
i Si Carter No. 3 jack switch (s. p. 
d.t.) 
i S2 Benjamin 8630 switch (s. p. 
s.t.) 
i S-M No. 701 color cable (5 
leads) 
i pair Benjamin No. 8629 shelf brack- 
ets 
i Bakelite Panel, 7 x 18 x | 
O rt inches 


t^Ljlr- 






'* S=5 

0' ' - 


5 






fl 








"o 


(ft)000+) 
II 


u 
<^^ 


-o ' 

M U 






tr 

E 

ro 


= |p^yr 






PI 

su 

x 




M v 


II 




i Small parts: 29 -fa R.H. 
^ o, N. P. machine screws f 


<s_ 

^B 


__^ r 






~ WCD inch 
2 6- R.H. N. P. machine 


CX 

J * 

JKKKKKL 


,fj 


WM screws if in. 

31 A nuts 
i spaghetti 
10 strips bus-bar 

2? luffS 


11 



F1G. 6 

Complete wiring diagram of the super-autodyne receiver. If this 

diagram is used in connection with the picture layout diagram, an 

error in connections is impossible 



Tools required: i hand-drill 
with drills and countersink, 
i soldering iron with rosin- 



The Super-Autodyne 



381 



core solder and non-corrosive paste, i side-cutting 
pliers, i screw-driver, hammer, and centerpunch. 

THE OSCILLATOR COUPLER AND GENERAL 
ASSEMBLY 

THE oscillator coupler may be made by 
winding two sections separated T Vinch 
apart on a 2|-inch bakelite or condensite 
tube; each section containing twenty-eight 
turns of No. 28 d.s.c. wire. The rotor coil 
also consists of twenty-eight turns of the same 
size wire on a i|-inch tube rotatable within 
the stator tube. 

As soon as the materials have been procured, 
each item should be carefully examined to 
see that all screws and nuts are tight, and lugs 
placed as shown in the photographs, so that 
those on the various instruments will point in 
the best directions for short leads. Socket 
springs should be bent up to make good con- 
tact with tube pins. Condenser bearings 
should be adjusted to give the desired tension. 

If the builder already has Benjamin sockets, 
the socket-shelf may be made up by drilling 
a piece of bakelite 17! x 4! x \ inch in accor- 
dance with Fig. 7. The bases should be 
removed from the Benjamin sockets so that 
they may be fastened directly to the sub-base 
with their original screws. On each terminal 
will be found a round knurled nut, a hex- 
agonal nut, and a round-headed screw. The 
screw should be put through the hole in the 
spring, pointing downward. The knurled 
nut is turned up on the screw under the spring, 
the screw pushed through its hole in the shelf, 
a lug placed over it if necessary, and the "hex" 
nut tightened up on the under side of the 
shelf. Care should be taken to prevent the 
spring from twisting as the nut is tightened, 
due to rotation of the screw. If this occurs, 
the socket will not ride evenly on its spring. 
Details of these operations may be obtained 
from Figs. 2, 3, and 4. Either uv-i9Q or 
standard uv-2oiA sockets may be used. They 
should be arranged so that their grid terminals 
come out at the left rear, as in Fig. 3. 

The front panel may be laid out in accor- 
dance with Fig. 8, using a rule and scriber 
after which the hole locations should be 
punched with a center-punch or nail, and a 
hammer. After drilling the holes, the panel 
may be grained with fine sand-paper and oil, 
rubbing in one direction until the original 
polished finish has disappeared. After wiping 
the panel off with alcohol, indicating marks 
for the dials may be scratched as in Fig. i, 
and filled with Chinese white. The sub panel 
should not be grained. 




FIG. 7 
Drilling dimensions for the sub-panel 



Radio Broadcast 




FIG. 8 

Panel drilling dimensions. If a meter is used with this set, which 
is strongly advised, the holes indicated should be drilled. The 



ASSEMBLY OF PARTS 

BEFORE starting with the as- 
sembly, the photographs 
should be very carefully studied, 
to see just how each part is put 
on, and just where each of the 
different parts go. If the S-M or 
Benjamin shelf is used, it will be 
unnecessary to drill any additional 
holes, as these shelves are supplied 
completely drilled for the parts re- 
commended. 

Figs, i, 3, and 4 should be ex- 
amined to see how the parts are 
arranged on the panel. The con- 
densers Ci and Ca, the Carter 
jacks and jack-switch and the Ben- 
jamin switch should be put on the 
panel, followed by the rheostat and 
potentiometer. The posts of these 
latter instruments should be on the 
bottom, and their contact arms 
should point upward when their 
indicating arrows do likewise. 

All parts should be put on the 
sub-panel as shown in the various 
photographs. In these C6, Cg 
and C 10 are shown inconveniently 
located. They should be placed in 
the positions indicated in Fig. 4, on 
the under side of the shelf. They 
are held to the sub-panel by ma- 
chine screws and nuts. Lugs placed 
between these condensers and the 
sub-panel may be soldered directly 
to the socket terminals in the case 
of CQ and Cio, since they run to 
plate and F of sockets 5 and V6. 
Condensers C3 and C4 may have 
one of their contacts connected to 
the grid terminals of sockets Vi 
and V4 respectively in the same 
manner. Lugs for C$ should be 
placed on the upper side of the 
shelf, as well as on one terminal 
each of C3 and C4, since some of 
the condenser connections will be 
made from above. 

WIRING THE RECEIVER 

TN WIRING the receiver, a well- 
1 tinned iron should be employed 
in conjunction with rosin-core sol- 
der. A small amount of paste may 
be used on each connection if de- 
sired; but not on any of the fixed 



o^ . . . . j 3llc . UUl IH-ii wii ny *-* m^ it^-^^ 

Weston double range voltrneter type 301, which may be used on V ronnections 

the panel requires the additional switch hole indicated condensers. Here, cor 



The Super-Autodyne 



383 



may be soldered to lugs, or to the condensers 
directly. 

Only two connections can be put on the 
panel alone. These are a connection between 
the rheostat and potentiometer, and one be- 
tween the potentiometer and Si. (See Figs. 
3 and 4.) Bus-bar should be used, straight- 
ened, carefully cut, and bent to proper length 
before any attempt is made to solder it in 
place. A long piece of bus-bar should not 
be soldered to a lug, and then bent and twisted 
until it reaches the other lug to which it is to 
be soldered. Each piece should be bent to 
fit properly, cut to size and then soldered 
in place. 

ASSEMBLING ON THE SUB-PANEL 

CTARTING on the sub-panel, all the 
^ wiring visible on it in Fig. 3 should be 
put on, the shelf then turned over, and the 
wiring necessary on the bottom put in place. 
All of the r.f. and a.f. transformer cases are 
connected together, and in turn connected 
to the negative filament line, which joins the 
minus lugs of all sockets, just as the positive 
line joins all the plus terminals of the six 
sockets. 
The Benjamin brackets should be fastened 



Li^fc 1 




FIG. 9 

to the sub base, and in turn loosely fastened 
of the panel. The lugs of the bypass conden- 
sers Cy and C8 are bent at right angles, and 
slipped in between the brackets and fastening 
nuts, as in Fig. 4. This makes a solid mount-? 
ing for these condensers, after the screws are 
tightened, as well as for the shelf-brackets. 
The balance of the wiring is then put in, 
running between the parts on the sub-shelf 
and those on the panel. This will not be 
found difficult, particularly if spaghetti is 
used only where there is danger of two wires 
shorting, or a wire shorting on an instrument. 




/ 



- 1- 

Ll 



Pivots 
Here 



V 



2 1 

ROTOR 

All Coils 
No. 28 DSC Wire 



Rotor 
Li 



Spring Brass 
, Bent To Shape > 




||f~ 


1 ' \~ 


f : i 

/ 


; 






1: 


1 


V" 




1 ! 


OSCILLATOR COUPLER 
CONSTRUaiON DETAILS 



Upper Coil 
L 2 



Lower Coil 




23 45 

DIRECTION OF WINDING 



DETAILS OF CONSTRUCTION OF THE OSCILLATOR COUPLER 



3 8 4 



Radio Broadcast 




FIG. I I 

A picture wiring diagram of the super-autodyne. The location of every wire 

in the circuit is shown. This should be used in connection with Fig. 6 

A C battery is used on the r.f. amplifier, point, the wire is broken, and a ten-inch 

It connects to the two flexible leads marked lead of lamp cord soldered to the potentio- 

C minus and C plus in the photographs, meter arm for the C plus lead and another 

No provision is shown for it in the diagram, similar wire soldered to the joint between 

except the point marked "Note." At this Cj and the A minus lugs of the 211 filter and 



The Super-Autodyne 



385 



its adjacent 210 transformer. This C bat- 
tery is 3 volts, and may be placed in the 
cabinet under the sub-shelf, since its leads 
should be short. It had best be wrapped 
in paper to prevent shorting on any of the 
wiring. For UV-2OIA tubes, these leads may 
be shorted and the battery eliminated en- 
tirely if the amplifier will oscillate without it. 
The remaining battery leads are brought out 
through a color cable, which should be coded 
in accordance with the data presented on 
page 1034 of the April RADIO BROADCAST. 
Unfortunately, there are a few manufacturers 
who have not yet adopted this coding for their 
cables. In Fig. 6, the colors of the various 
wires in the cable used for different voltages 
are given. This was for one particular make 
of cord, used on an experimental set. It will 
be noticed that the black lead with red tracer 
is used for three connections, which are made 
between the batteries themselves by means 
of other wires. 

ACCESSORIES AND TESTING 

ASSUMING the receiver to have been 
wired, it is ready for test. The addi- 
tional material required is as follows: 

6 Radiotron tubes, uv-2OiA, or uv-icjg. ov-3 
De Forest tubes may be substituted for 199*5, but 
will require a standard-base socket shelf. 

i A-battery. This may be a storage battery, 6 
volts, 90 ampere hours for uv-2oiA*s, or it may 
be the battery used in an auto, tapped by means 
of Lynch Leads. For dry cell tubes, three dry 
cells may be used, or, better yet, for home in- 
stallation six in series-parallel. 

1 B-battery. For permanent installation 90 
volts, of large size 22, or 45 volt batteries should 
be used. For portable work, 6y| volts will be 
sufficient, of medium or small-size batteries, 
since the current drain is but 12 milliamperes 
for 20 1 A tubes, and 9 milliamperes for 1995. 
(90 volts will give only slightly more volume 
than (f]\, so it is hardly worth while to carry 
around the extra 22-volt battery. 

2 C-batteries. One 3-voIt battery required in the 
set box for the r.f. amplifier, and one 4^-volt 
battery for the a.f. amplifier. 

i Loop with center tap. Any good tapped loop 
may be used, or one may be made by winding 
16 turns spirally on a form about 24 inches 
square, tapped at the center, with j inches 
between turns. This loop with eighteen turns, 
T\ inches apart, may be wound on the back 
of a cabinet large enough to hold the set, with 
the batteries beneath if desired. 



i Loud speaker. The small Amplion is recom- 
mended for portable work as it is a most excellent 
speaker, and delivers very good volume and 
quality. For home use, the Western Electric 
cone speaker is best, with its leads shunted by a 
.0075 mfd. condenser. 

i Phone plug. 

I Set Lynch Leads if the set is to be operated in a 
car,' using the starting and lighting battery. 
The Lynch Lead may be made up from any 
double conductor wire. Several types of wire 
can be used, but the flexible, rubber covered lead 
is recommended. The wires, which should be 
colored for ease in identification, should be 
scraped on one end, for connection to the fila- 
ment posts on the receiver. The other end of 
the lead should be connected to a plug which 
will fit into the dashboard connection to the 
automobile storage battery. 

i 7 inch x 18 inch x 7 inch mahogany cabinet. 




200 250 30Q 350 400 450 500 550 600 
WAVELENGTH IN METEKS 

FIG. 12 

Typical tuning chart of a super-autodyne. The 
curve marked "Loop S" is for the loop condenser 
with the switch in the "L" position. Only one 
curve is shown for the oscillator. The curve em- 
bracing the upper heterodyne points would parallel 
the one given, starting about four degrees higher at 
250 meters and ending about thirty degrees higher 
at 530 or 540 meters 

CONNECTIONS 

THE A battery should be connected to 
its leads, one tube inserted in a socket, 
switch S2 closed, and rheostat R4 just turned 
on. If the tube lights, it should be moved 
from socket to socket to see that all A connec- 
tions are correct. The positive battery lead 
should then be connected to the 845 and B 
90 posts. If the tube lights, the wiring or 
assembly is faulty and should be checked. 
The tube should only light when the A battery 
is connected to the A leads. 

The remaining batteries may be connected, 
and the loop leads run to posts B i, 62, and 83. 
If the loop is spiral, Bi goes to the outside 



386 



Radio Broadcast 



lead, 82 to the center and 83 to the inside. 
When switch Si is to the left, or short position, 
only half the loop is used. When it is to the 
right, the whole loop is used. This means 
all low wave stations up to 380 meters will 
come in on dial C2 from o to 100 degrees. 
Stations from 350 meters up will come in on 
C2 with switch Si thrown to the right, or long 
position. This means that in the long posi- 
tion, C2 will read about 20 for 345 meter 
stations, and about 70 for 536 meter stations. 
On the short position, C2 will read about 85 
for 345 meter stations, and about 45 for 270 
meter stations. These figures are approxi- 
mate, but show that to cover the entire wave- 
length range, C2 must be varied from o to 100 
degrees to go up to 370 meters with Si to the 
left, then Si turned to the right and the re- 
maining wavelength range secured by varying 
2 again from o to 100, allowing, of course, 
for over-lapping. Ci, the oscillator, starts 
around 18 for 270 meters, and brings in the 
lower heterodyne point for 536 meters at about 
70. Two points can.be found for each station 
on this dial, which will help in tuning, as 
when interference is experienced on one point, 
the other may be used. 

TUNING AND TESTING THE COMPLETED RECEIVER 

THE first test should be to check tube Vi for 
oscillation. Insert only tube Vi, set R4 just 
on and connect the phones in series with the 845 
lead. Then touch lugs 3, or 6 of the coupler. If 
a plucking sound is heard, this tube is oscillating. 
If not, adjusting the rotor coil will cause it to 
oscillate. When this rotor winding is in the same 
plane as the stator windings, turning it 180 degrees 
around will either start or stop oscillation. When 
once set to produce oscillation, this coil should never 
be touched. If the tube squeals at low settings of 
Ci, reduce Ri to .25-megohms, or try another 



.5 megohm leak. Use the highest value of leak 
possible (up to i meg). The receiver will prob- 
ably squeal below 10 degress on Ci in any case. 
R2 is not critical and may vary from i to 3 megohms. 
With tube Vi oscillating constantly, insert the 
remaining tubes in the set, turn the rheostat seven- 
eights on for 20 1 A tubes, or on one-third for 190/5, 
and rotate the potentiometer from positive to nega- 
tive. If both Ci and C2 are set at 100 degrees, a 
plunk will be heard at some point as R3 is adjusted, 
indicating amplifier oscillation. If Ci is adjusted, 
squeals will be heard. R3 should be set with its 
arm just positive of the point where squeals can 
be heard, and either left set at this point, or used to 
control volume. Now, with Si to the right, and 
Ci set at 50, rotate C2 over its entire range. A 
click will be heard near the center of its scale. The 
condenser CX connected between terminals 3 and 
4 of the coupling unit should now be slowly turned 
out in small steps until rotating C2 fails to produce 
a click. The receiver is now balanced and CX, CX 
should never be touched unless tube Vi is changed. 

In tuning, C2 will appear rather broad, which is 
correct, while Ci will be extremely sharp. This 
permits of extremely easy logging, since C2 need 
only be set approximately correct, and Ci rotated 
in order to find a station. The chart printed on 
page 385 will help in preliminary tuning. The 
set will log definitely, and a station once heard may 
be brought in again at the same settings of Si, Ci 
and C2, providing CX, CX have not been tampered 
with. 

Due to the sensitivity of the circuit, a small 
amount of hand capacity may be noticeable on Ci. 
This may be overcome by grounding the negative 
filament line to a piping system, or it may be com- 
pensated for by tuning-in a station, increasing Ci 
slightly until the volume begins to decrease, and 
removing the hands from the set. The signal will 
then return to full intensity. It will be evident in 
those few cases where it may be encountered, only 
on weak, low wave stations, and is seldom bother- 



An Explanation 

THE similarity in name of Dr. Walter Van Braam Roberts and J. E. Roberts has led to some confusion among 
the readers of RADIO BROADCAST. Doctor Roberts, of Princeton University, is responsible for the inception 
and the design of the Roberts Knockout receiver. Doctor Roberts wrote two articles describing this receiver 
which appeared in the April and May, 1924, RADIO BROADCAST. 

Immediately after the publication of these two articles, a great deal of interest was shown by radio con' 
structors all over the country in the design and operation of the set. Many investigators started building the 
receiver, making additions and alterations according to their own ideas. One of these enthusiasts was J. E. 
Roberts, of Cleveland, Ohio, who prepared an article describing how to build the original two'tube circuit in a 
cabinet with an additional stage of audio amplification, making three tubes. 

We have received many letters from residents of Cleveland and vicinity who have taken issue with what 
they regarded as an unfortunate use of the similarity of last names of these two men. The situation which 
drew the protest was in Cleveland and other cities. And in especial, a number of our correspondents did 
not like printed matter which was distributed by a Cleveland radio shop. 

Mr. J. E. Roberts has no connection with RADIO BROADCAST other than that of a former contributor to its 
pages. The only approved models of the Roberts Knockout circuit have been described in the magazine. We 
can take no responsibility for any printed matter or representations of individuals relative to this circuit released 
by other sources than this magazine except that of approved manufacturers of parts which may be used in the 
Roberts circuit. 





A New Method of Radio 
Frequency Amplification 

The Theory of Various Arrangements for Neutralizing Tube Capacity in 
Radio-Frequency Amplifier Circuits and a Discussion of a New Method An 
Arrangement for the Measurement of Amplification Constant and Impedance 

BY C. L. FARRAND 



'T'HIS paper of Mr. Farrand's was presented More a meeting of the Radio 
* Club of America, in New York, and involves an interesting history 
and discussion of neutralising methods in radio frequency amplification. 
Toward the end of the paper, the author also describes a method for connecting 
and using a vacuum tube voltmeter which should be particularly interesting to 
many readers. In a later number we shall print another article by the same 
author, dealing with his later investigations. The papers presented before the 
Radio Club appear from time to time in this magazine. The editor assumes 
no responsibility for statements made by the authors of the papers, but is very 
glad indeed to present them to the readers of RADIO BROADCAST. THE EDITOR 




IT IS the purpose of this paper to present 
a new method of radio frequency ampli- 
fication, together with the necessary data 
for the design and construction of the circuits. 
Tuned radio frequency amplification is not 
new. See Schloemilch and Von Bronk, United 
States Patent No. 1,087,982. This method 
has been used with considerable success, 
more difficulty being experienced as the 
number of stages were increased. These 
difficulties were due to incipient couplings 
in the amplifier circuits, either between the 
input and output circuits of a single tube or 
between the input and output circuits of 
more than one tube. These couplings are 
either electro-magnetic or electro-static, as in 
a good design, resistance couplings are elimi- 
nated. The magnetic couplings can best be 
taken care of by disposing the transformer 
windings so that their axes are at right angles, 
and on the same center line, with reasonable 
distance between windings. 

Static couplings between the input and out- 
put circuits of the tubes can be eliminated by 
shielding in all cases excepting the inherent 
capacity coupling of the tube itself. From 
general considerations it is apparent, having 
been brought out before, that there are three 
capacities in a three-electrode vacuum tube, 
two of which act in shunt to the input and out- 
put circuits respectively, and the third which 
is the grid to plate capacity, acts as a coupling 
between the input and output circuits. See 



Fig. i. To eliminate this coupling, it is 
necessary to resort to balancing arrangements 
or to additonal circuits which will nullify 
the influence of the coupling current flowing 
through this capacity. The coupling in- 
creases with frequency, and, it is in the broad- 
casting range and shorter waves that the 
most difficulty is experienced. 

Various methods have been suggested for 
neutralizing or balancing the tube coupling. 
Hartley (R. V. L. Hartley, United States 
Patent No. 1,183,875) has suggested a mag- 
netic balance, which is the equivalent to a 
reverse tickler coil. See Fig. 2. 

By this method, the coupling effect of the 
grid-to-plate capacity of the tube is balanced 
by an equal and opposite magnetic coupling 
between the input and output circuits. This 
condition holds for only one wavelength. 
In the Figure shown, the static tube-coupling 
increases with frequency, while the magnetic 
coupling remains constant. 

THE RICE METHOD 

RICE (C. W. Rice, United States Patent 
No. 1,334,118) has suggested a capacity 
balance which is in effect Fig. 3. By this 
method, the coupling effect of the grid-to-plate 
capacity is balanced by a capacity of equal 
value connected between the plate and an in- 
put coil being opposite potential to the grid. 
Hazeltine (L. A. Hazeltine, United States 
Patent No. 1,450,080) has suggested a 



388 



Radio Broadcast 




r II P 


*"s5l 


G II P 


II 


O 




^r^ 


o 




= Ir 


o _ 


4 _ 




c 

_ c 




O( 


7 




- 


" C 

o 




0< 


o 






o 




^ V c J 








F F 


FIG. I 



capacity balance wherein the effect of the 
grid to plate capacity of the tube is balanced 
by means of an output transformer. Fig. 4. 
Here the coupling effect of the grid-to- 
plate capacity is balanced by a capacity con- 
nected between the grid and an output coil 
having a potential opposite to the plate. 



G II P 


^^f 
O 
O 


o 




o 




^r^ 


o 


o 

Q 




. > 






Qj 
7 
O 


^* 






F 


r? 



f 

o 
o 
o 
o 
o 
o 


Hi 

7 








FIG. 2 

The output coil is the secondary of the trans- 
former supplying the next tube and has a 
ratio of turns greater than unity to satisfy 
the impedance relation, so that it is necessary 
that the value of the balancing capacity be 
chosen to equal the grid-to-plate capacity 
divided by the voltage ratio of the output 
transformer. 





nr~ 
















II 


^ 


r 




o 






o 




O 




o _ 


^ - 





o 

Oj 


/ 


o 




^ 


7 






- o 




7 










F 


o 

2 




>o 
o 

c 





FIG. 3 

The disadvantages of the above methods 
are that, particularly on short wavelengths, 
it is very difficult to maintain a balance 
when more than one stage of radio frequency 
amplification is used. This is due to stray 
capacities, which tend to upset the balance 
of the circuit. Oscillations then result. Dif- 
ficulty of this sort is also brought about by 
the variation of grid-to-plate capacity of 
commercial tubes, which vary so much that 



a balance obtained for one tube may not hold 
for another. 

A NEW NEUTRALIZING SCHEME 

THE method of nullifying the effect of the 
grid-to-plate capacity of three-electrode 
vacuum tubes described in this paper does 
not depend upon a capacity balance and is 
free from the disturbing effects described 
above. The method involves a resistance 
connected between the grid and plate of the 
tube as in Fig. 5. 

The effect of this arrangement is to change 
the phase of the coupling current flowing 
between; the input and output circuits, thereby 
reducing the energy transfer or feed-back 
between these circuits and causes the remaining 
energy to be absorbed as quickly as it is trans- 
ferred or fed back. The value of resistance 
necessary to nullify the grid-to-plate coupling 
is dependent upon the design of the tube, as 



o 



^ 

o 


= 


II 

F 




o 
o 






o 
o 



^ 


II 






FIG. 4 

well as the circuits. This resistance value 
is not critical. For the storage battery tubes 
now in commercial production, a resistance 
ranging between twenty-five and thirty-five 
thousand ohms gives satisfactory performance 
for multistage operation. The value for mul- 
tistage operation is slightly lower as it is 
possible to take care of the stray overall 
coupling by a slight reduction of resistance. 
One hundred thousand ohms is a satisfactory 
value for the present dry cell tubes and 
may vary between ninety and one hundred 
and twenty thousand ohms. 

The resistance should preferably be non- 
inductive and of low capacity. Present forms 
of conducting coated-paper resistances, and 



A New Neutralizing Scheme 



389 



carbon filament wound lavite resistances are 
satisfactory. 

The circuit for a two-stage amplifier is 
shown in Fig. 6. 

It will be noted that a condenser is inserted 
in series with the resistance between grid 
and plate to prevent the plate battery from 
flowing through it to filament. The con- 









o 




p 


<z 




/ _ 




c 
_ c 


i 7 






c 
c 







r 


c 




FIG. 5 

denser is purely a blocking condenser and 
may range in value between one microfarad 
and one one-thousandth of a microfarad, and 
is only needed to permit the amplifier tubes 
to be operated from a common plate battery. 
The transformer windings should preferably 
be tightly coupled, although this is not 
necessary as long as a suitable voltage ratio 
is maintained between primary and secondary. 
A suitable design consists of one hundred 
turns of No. 26 B & S gauge wire on a cylin- 
drical tube, two inches in diameter and about 
two and three quarter inches in length. 
This is the secondary winding. The primary 
should be wound with about twenty-five turns 
of the same size wire on a concentric cylindri- 
cal tube of about one and three quarter inches 
in diameter. It is preferable to have the 
primary winding the same length as the sec- 
ondary winding is when enclosed by the secon- 
ary winding. This arrangement gives the 
tightest coupling, although the same result 
may be secured by using more primary turns 
and less coupling. This will be discussed 
more in detail later. The primary is, in 
practice, wound opposite to the secondary. 
That is to say, if the secondary is wound 
clockwise, the primary is wound counter- 
clockwise, or vice versa. The end of the 
primary winding directly under the grid end 
of the secondary should be connected to the 
plate battery. The other terminals follow 
as usual. The secondary tuning condenser 
should have a capacity of approximately two 
hundred and fifty micro-microfarads. The 
increase in intensity produced by each stage 
of radio frequency amplification as outlined 
above is nearly as much as that produced by 
each stage of audio frequency amplification. 
This is a very general statement but holds 



fairly closely for radio stages up to three or 
four before the detector when compared one 
stage at a time with one and two stage of 
audio after the detector, although the voltage 
amplification of the radio stages were only 
about twelve each while the audio amplifiers 
gave approximately twenty per stage. 

This indicates that while the detector char- 
acteristic is not linear it is far from a square 
law. 

REGENERATIVE AMPLIFICATION IN THIS CIRCUIT 

IN ADDITION to the radio frequency ampli- 
* fication of each stage, it is possible to obtain 
a regenerative amplification which is equiva- 
lent in increased volume to the addition of 
two audio stages on a signal of average in- 
tensity. Fig. 7 shows the circuit of a receiver 
consisting of three stages of radio frequency 
amplification, a detector and two audio stages. 
The regeneration here shown is provided 
for by omitting the nullifying resistance of 
the third radio stage, and controlling the 
feed-back due to the tube coupling by means 
of a potentiometer on the grid of this same 




FIG. 6 

tube. This gives very satisfactory operation. 
Equally satisfactory operation may be had 
by the use of a variometer in the plate of the 
detector tube in the usual manner. In this 
case the nullifying resistance must be used 
across the grid and plate of the third tube as 
well as across the first and second. In the use 
of three stages of radio frequency amplifica- 
tion without regeneration it is not necessary 
to take any particular precautions except to 
dispose the transformer windings at right 
angles and to use care to provide for short 
grid leads, and that the grid lead of one tube 
does not run close to the grid lead of another 
tube. If such precautions are not taken, the 
amplifier may regenerate and oscillate at the 
lower wavelengths. It will be found that 
when the regenerative feature is added to the 
amplifier or detector, better control of the 
regeneration will be obtained if the receiver 



3QO 



Radio Broadcast 



has first operated satisfactorily without re- 
generation. This means that the interstage 
coupling has been reduced to a minimum and 
that this provides for the localization and 
better control of the regeneration. In the 
operation of a receiver as outlined above using 
two or three stages of radio frequency ampli- 
fication in addition to regeneration, the local 
oscillations produced during the adjustment 
of the regenerative amplifier or detector tube 
do not radiate from the antenna in any 
noticeable degree sufficient to cause inter- 
ference with near-by receivers. As a typical 
example of this, a receiver has been operated 
on an outdoor antenna approximately forty feet 
from an adjacent antenna which is paralleled 
for approximately twenty feet. Both anten- 
nas were approximately forty feet high and had 
a total length of about one hundred and 
twenty five feet. The beat produced by the 
receiver was noticeable on the receiver of the 
adjacent antenna only on reception from sta- 
tions nearly one thousand miles distant and 
then was not particularly objectionable. 

Due to the low input impedance of the 
present commercially produced tubes and the 
consequently large damping effect produced 
thereby, the tuning of transformers is broader 
than would be anticipated. While objec- 
tionable in single-stage operation, the tuning 
sharpens considerably with the addition of 
several stages until very reasonable selectivity 
is obtained. It is also possible and extremely 



practicable to tune the transformers by means 
of condensers on a common shaft as suggested 
by Hogan. (J. V. L. Hogan, United States 
Patent No. 1,014,002). This has been 
done very successfully with three stages of 
radio frequency amplification using an aperi- 
odic antenna input by means of four conden- 
sers on a common shaft and with six stages of 
radio frequency amplification by means of 
eight condensers on a common shaft. In the 
latter case one condenser was used to tune 
the antenna separately which was loosely 
coupled to the amplifier input circuit. The 
condensers were electro-statically shielded 
from each other, and the tube coupling capaci- 
ties were nullified by means of the resistances 
of values given above. 

Additional improvements in selectivity have 
been made, which, unfortunately cannot be 
disclosed at the present time and will have to 
form the subject of a later paper. It might 
be mentioned that by these means, reception 
without regeneration of five hundred and nine- 
meter stations in Philadelphia, through a 
local four hundred and ninety two-meter 
station, is entirely practicable. 

MEASUREMENTS OF AMPLIFICATION CONSTANT 
AND IMPEDANCE 

A METHOD of measuring the voltage 
** amplification of radio-frequency ampli- 
fiers during the writer's experiments became 
very desirable. After various methods were 




MR. FARRAND DEMONSTRATING HIS RECEIVER 

Before a meeting of the Radio Club of America in New York. The entire back of the panel is shielded, as 
can be seen from the photograph. The condensers are all tuned by one knob which controls a gear arrange- 
ment. Nine tubes are used in this model 



Measurement of Amplification Constant 



391 




FIG. 7 



considered and used, the peak volt-meter was 
selected as giving most promise. This 
method consisted in determining the actual 
voltages of the grids under working condi- 
tions by use of a three-electrode vacuum 
tube. The use of three-electrode tubes as 
volt meters is well known and has been des- 
cribed before. 

The voltmeter was calibrated as follows: 
A uv-2oiA tube was used with approximately 
67 volts on the plate and about 12 volts nega- 
tive on the grid. The plate current was then 
normally about 10 micro-amperes. A known 
radio frequency voltage was applied to the 
grid and the grid negative voltage was in- 
creased until the plate current reached a 
known value which was the 10 micro-amperes. 
The increment of negative grid voltage was 
recorded. It was found that the tube would 
always reproduce these conditions with the 
same voltages. In this manner the voltmeter 
was calibrated in terms of increments of nega- 
tive grid voltages vs. applied root mean square 
values. To save interpolation the measure- 
ments of impedance and voltage amplifica- 
tion were made with the same r.m.s. value of 
voltage applied to the voltmeter. This value 
was set at .5 volts and the input voltage of 
the preceding tube changed until this value 
was produced. 

The following is a diagram of the voltmeter 
and circuit used for these measurements: 

The capacity of the voltmeter is very small, 
since it is only the grid-to-filament capacity 
of the tube plus small lead capacity which 
would approximate 10 to 20 micro-micro- 
farads. This capacity is connected in parallel 
to the tuning condenser and therefore does 
not affect the result. The impedance of the 
voltmeter can be considered as purely resis- 
tance in nature and very high, probably sev- 
eral, megohms, as the grid has in excess of 10 
volts negative applied. 



MEASUREMENTS WITH THE VACUUM TUBE 
VOLTMETER 

THE voltage amplification per stage is the 
voltage of the grid of the second tube 
divided by the voltage of the first tube. It 
was necessary to determine that the imped- 
ance of the plate circuit of the second tube 
would not affect the impedance of its grid, 
as in multistage operation the plate circuit of 
the second tube would be tuned by a trans- 
former to supply the grid of the succeeding 
tube, and if this high impedance caused by 
the plate tuning of the second tube affected 
its grid to filament impedance, the measure- 
ment as outlined would not hold. Non- 
inductive resistances of 10,000 ohms were 
inserted in the plate circuit and the plate 
voltage was maintained constant by adding 
sufficient battery to take care of the resistance 
drop, and at radio frequencies this was found 
to affect the input impedance of the grid very 
considerably. This corresponded somewhat 
to the results obtained by Weinberger. 
(J. Weinberger, Proc. I. R. E., page 584, sec. 
1919.) It was thought that this change of 
impedance might be due solely to capacity 
coupling of the tube causing feed-back action, 
therefore the applied frequency was reduced 
to 1000 cycles and it was found that at this 
frequency, the grid-to-filament impedance 
was independent of the plate load impedance. 
It followed, therefore, that any influence of 
the plate load on the grid impedance was due 
to regeneration and would disappear when the 
regeneration was nullified. 

The measurements of voltage ratio by this 
method would hold and give. the true radio 
frequency amplification without feed-back as 
long as the amplifier was non-regenerative. 

The voltage ratio was determined for. a 
tuned radio-frequency transformer as shown 
in the Figure and the radio frequency ampli- 



392 



Radio Broadcast 




FIG 



fication factor per 
stage obtained. A 
similar transformer 
was then connected 
to the plate of the 
second tube and ar- 
ranged to supply the 
grid -to -filament cir- 
cuit of a third tube 

which was connected as the second tube had 
been in the first case. The voltage on the grid 
of the second tube was found to be decidedly 
higher due to feed-back action. A nullifying 
resistance was then connected from grid to 
plate of the second tube and adjusted until 
the voltage of its grid equalled the original 
voltage as given when the output of the plate 
was shorted by switch "S." The resistance 
had then nullified the feed-back action due 
to the natural capacity between the grid and 
plate of the tube and the voltage amplification 
obtained was the original non-regenerative 
radio frequency amplification. The value of 
nullifying resistance thus obtained was found 
to be between 30,000 and 50,000 ohms for 
uv-2oiA tubes and between 80,000 and 
120,000 ohms for uv-igg and WD-II tubes 
The values of resistance approximate the ca- 
pacity coupling reactance of the tubes, i. e., 
the grid to plate capacity in ohms at the 
operating frequency. 

IMPEDANCE VALUES OF COMMERCIAL TUBES 

v> ~pHE maximum voltage amplification de- 

* termined and the turn ratios for maximum 

amplification lead to the conclusion that the 



grid to filament im- 
pedance was much, 
lower than antici- 
pated, when the grid 
was connected to neg- 
ative filament. Since 
the grid to-filament 
impedance was al- 
ways shunted with a 

secondary tuning condenser, it could be consid- 
ered as purely resistance in nature. It was de- 
cided to determine this impedance value for 
commercial tubes. The peak voltmeter method 
was very well suited to this measurement as it 
was only necessary to substitute a known non- 
inductive resistance for the tube, retune to 
compensate for the reduction of capacity of the 
grid-to-filament and adjust the resistance until 
the voltage of the grid of the second tube was at 
its original value. The resistance thus deter- 
mined was then equal to the resistance of the 
grid-to-filament path of the tube. These 
values for uv-2oiA tubes with grid connected 
to negative filament were found to be between 
120,000 and 150,000 ohms with 130,000 ohms 
as a fair average. This accounted for the 
broadness of tuning of non-regenerative radio- 
frequency amplifiers, as with a circuit using a 
condenser of 250 micro-microfarads maximum, 
for the broadcasting range, the condenser 
reactance at 400 meters is approximately 
1800 ohms and the effect of 130,000 ohms in 
shunt to such a circuit is the same as if ap- 
proximately 25 ohms had been inserted in 
series with the condenser and inductance, and 
consequently produces very large damping. 



How to Build Radio Broadcast's 
Phonograph Receiver 



BY ARTHUR H. LYNCH 



IN THE June RADIO BROADCAST we de- 
scribed a receiver which has been de- 
signed to fit in any phonograph. This 
article, the second of the series describing 
this receiver, deals with the actual construc- 
tion of the apparatus and indicates by illus- 
trations what has been done in RADIO BROAD- 
CAST'S Laboratory to apply this unit to a 
number of phonographs. 

It may be seen from the illustrations accom- 
panying this article, that it is not necessary 
to use one specified unit in building this re- 
ceiver. For example, any good audio trans- 
former will function satisfactorily in the re- 
flex stage, and any good push-pull transformer 
will work in the amplifier arrangement. In 
the diagrams shown in Figures 23-A and B, the 
panel and sub-base arrangements have been 
designed to accommodate practically any 
.0005 mfd. condenser, and almost any tube 
sockets and other units which make up the 
assemblage. 

RADIO BROADCAST'S Phonograph Receiver 
has not been designed to satisfy the demand 
for the ultimate in radio reception. It will, 
however, bring in excellent quality with very 
good volume and at the same time cover a 



very reasonable wavelength range. With 
a similar set operated here on Long Island 
during the month of April, and using but two 
tubes, the following log was made in one hour 
and twenty minutes: 



DIAL SETTINGS 

12-12 

15-15 

19*19 

21-21 

22-22 

28-28 

31-31 

32-32 

34-34 
39-39 
41-41 
42-42 

45-45 
46-46 

49-49 
52-52 

57-57 
60-60 
62-62 
64-64 
69-69 
80-80 



CALL LETTERS 
WC AD 
WEAN 
WTAS, WPG 
KDKA 
WGBS 
WLS 
CFCA 
WHN 
WGN 
WTAM 
WLIT 
WOR 
CHYC 
PWX 
WLW 
WOS 
WJZ 
WCAE 
WCAP 
WEEI 
WEAF 
WNYC 



When this log was made, the set was tuned 
with but two controls. The rheostat and 




RADIO BROADCAST Photograph 



FIG. I. SUB-PANEL ASSEMBLY 

The photograph illustrates how the rheostat panel and tube sockets are mounted upon the brackets. AH con- 
necting leads to the. main panel are temporarily coiled and labeled until this assembly is ready for further use 
This is the "Robert-Unit" made by the Radio Research Laboratories 



394 



Radio Broadcast 



tickler controls were not used. It will be 
noted that the positions of the two dials 
throughout this log coincide over the entire 
broadcast range. 

HOW TO ASSEMBLE AND WIRE THE SUB-PANEL 

BEFORE drilling holes in the sub-panel 
for mounting the various units it must 
hold, it is advisable to place the sub-panel it- 
self upon the brackets which are going to 
support it on the main panel. Then place 



the tube sockets in their proper places and if 
necessary, secure them with a few pieces of 
string. Then turn the sub-panel upside down 
and mark off the positions to be occupied by 
the transformers, but make certain that there 
is plenty of space surrounding each unit to 
permit the wiring to be done easily. 

It is good practise to do as much wiring 
on the sub-panel as possible before perma- 
nently attaching it to the panel as shown in 
Fig. i. 




FIG. 2. A TEMPLATE FOR THE SPIDER WEB COILS 

Exact size. The windings for these coils, as used in various parts of the Roberts circuit and indicated 
by the letters are as follows: A (antenna coil): 40 turns No. 22 DCC wire tapped 1-2-5-10-20-30-40; Si : 
44 turns No. 22 DCC wire; N: 20 turns No. 26 DCC wire; P: 20 turns No. 26 DCC wire (two wires of N 
and P are wound parallel as a pair); 82: 44 turns No. 22 DCC wire; T: 18 turns No. 22 DCC wire. Coils A, 
Si, 82 and T are each individually wound under two and over two spokes of the form. The NP coil is 

wound under one and over one spoke 



How to Build Radio Broadcast's Phonograph Receiver 



395 




RADIO BROADCAST Photograph 
FIG. 3A-B. A HOME MADE COIL UNIT 

Constructed from odds and ends around the laboratory. The 
binding posts to which flexible leads from the coils are attached 
are mounted on bakelite supports. Coupling between the pri- 
mary and secondary is obtained by loosening the hexagon nuts 
and shifting the position of the primary coil 




THE PANEL 

IN ARRANGING the units on the panel the 
layouts in Figs. 21 -A and B will be found 
very helpful. Then, too, it is good practise to 
wire as much of the panel as possible before the 
sub-panel is attached. If this plan is followed 
the balance of the wiring will be brought to 




a minimum and the attendant work will be 
much simplified. 

HOME-MADE COILS 

E of the simplest forms of coil for home 
construction and which may be used 
in this receiver is the spider-web coil. The 
form dimensions are given in Fig. 2. The 
various wire sizes, and the number of turns 
to be wound on each coil are indicated in the 
caption of Fig. 2 on page 394. 

A simple and good method of mounting and 
coupling home made coils has been designed 
by John B. Brennan, Technical Editor of 
RADIO BROADCAST. This system is illus- 
trated in Fig. 3A-B. 

ANTENNA SWITCH 

IN ORDER to compensate for the use of 
antennas of various lengths, a switch is 
placed in the antenna circuit to alter the 



RADIO BROADCAST Photograph 
FIG. 4. THE TAP SWITCH 
The antenna coil sections may be included in the 
primary circuit by means of this switch which is 
mounted upon a piece of bakelite supported within 
the coil unit as shown above. This is a control 
which need not be varied once the correct adjust- 
ment has been obtained. Therefore, it is not neces- 
sary to mount the switch upon the panel proper 




IADIO BROADCAST Photograph 

FIG. 5. THE BRACKETS 

For supporting the sub-panel upon which is mounted 

the transformer, etc. The arrows indicate the 

points at which the projected parts of the brackets 

are removed 



396 



Radio Broadcast 



number of turns in the primary of the antenna 
coupler. By the proper adjustment of this 
switch, the two main control dials, the an- 
tenna and the radio-frequency tuning dials, 
will be found to read approximately the same 
for given stations within the tuning range. 
This feature is particularly valuable when the 
receiver is used by an inexperienced person. 
In order to make the layout of our phonograph 
model more symmetrical we have placed this 
switch behind the panel as shown in Fig. 4. 
When the receiver has been completed it 
should be tested before it is placed in its cabi- 
net and the proper setting for the antenna 
switch should be determined. 

RUBBER BUSHINGS 

WHERE cushion sockets are not used, 
sponge rubber, which may be procured 
from many dealers, or from several radio mail 
order houses or rubber companies, is ideal for 

FIG. 6. THE BUSHINGS 

Note that the sub-panel is raised up from the 
brackets by means of the knurled nuts taken from 
the socket terminals and which are used as bushings. 
This is necessary so that the bottom of the audio 
reflex transformer mounted out of 
sight in this photograph at the far end 
of the sub-panel does not project 
beyond the bottom of the panel 





RADIO BROADCAST Photograph 



RADIO BROADCAST Photograph 



FIG. 7. THE BATTERIES 

Are here shown stacked up to fit 
underneath the sub-panel. This re- 
ceiver may be used as a portable outfit, 
i^-volt dry cell tubes are used 



cushioning the tubes to prevent 
microphonic noises which are 
sometimes noticed where rigid 
construction is used. Flexible 
wiring is employed between the 
main and the sub-panels. This 
is necessary to insure the suc- 
cess of the cushioning. An ideal 
system for applying bushings of 
this kind is shown in Fig. 6. 

TUBE IRREGULARITIES 

TUBES, particularly those 
which have been in use for 
some time, are often found to 
be anything but uniform in per- 
formance. A tube which may 
do very well as a radio or audio 
amplifier may not function prop- 
erly as a detector and vice versa. 
Therefore, the tubes must be 
tried in various positions until 
the best combination is found. 



How to Build Radio Broadcast's Phonograph Receiver 



397 




-8 45 90 US 



FIG. 8. THE WIRING ARRANGEMENT 



From this circuit it will be seen that the push-pull amplifier circuit differs from the original four-tube hook-up. 

The balance of the circuit, however, remains the same. In this illustration Amperites have been substituted 

for the rheostat controlling the two push-pull tubes. Also a condenser Cy has been added in the circuit. 

This condenser will effectively prevent the amplifying transformer from singing 



ABOUT PLATE AND GRID VOLTAGES 

THE plate voltage on the radio and audio- 
amplifier tubes is not critical and for prac- 
tical purposes in the home we have found 90 
volts to be ideal. It is unnecessary, unless 
great volume is required, to use more than 90 

-BINDING POST STRIP 



volts in any part of the circuit, and it has been 
found that a jumper between the two last 
terminals on the binding post strip, as indi- 
cated by the dotted line in Fig. IO-A, serves to 




Variable Connection For 

Proper Detector Plate Voltage 

-AB 



B 45 



'v 6 Volt 
Storage Battery 



45 \CBat' 

'B45 

Remove Dotted Line 

Connection When Using 

Only 90 Volts On Both 

Amplifier Posts. 




Symbolical 
Representation ^ 



Amp. 
B+13& 



FIG. IOA-B THE JUMPER CONNECTION 
When it is desired to use but 90 volts upon the am- 
plifier tubes the connections to the B batteries must 
be changed as shown in Fig. IO-A. The connection 
represented by the dotted line is removed and a 
jumper connection is fastened between the amplifier 
B plus binding posts. Fig. IO-B shows the con- 
nections when the full 135 volts are used 

. BINDING POST STRIP 



FIG. 9. TESTING PLATE VOLTAGE 
For some detector tubes it is necessary to employ a 
definite plate voltage which must be ascertained by 
actual test. The pointed lead attached to the B 
plus binding post may be touched upon the several 
taps of the first 45 volt B Battery until the desired 
value of plate voltage is obtained 




- 6 Volt 
Storage Battery 



45 Shows Connections 
When Full 135 Volts is 
Used 



FIG. II. ANTENNA SUBSTITUTE 

For an outside antenna called the Antennaphone. 1 1 
is only necessary to place a metal disc under a desk 
telephone to obtain an antenna installation. The 
disc is then connected to the antenna binding post 
on the receiver. Wire is supplied for this purpose 



> 9 8 



Radio Broadcast 




RADIO BROADCAST Photograph 

FIG. 12. ANOTHER ANTENNA SUBSTITUTE 
This unit is r.ierely plugged in to any electric light lamp 
socket. Several methods of use are shown in Fig. 13 



bring this voltage into play on all tubes but the 
detector. 

Caution: When using the jumper between 
the terminals in the diagrams marked minus 
90 and minus 135, as indicated by the dotted 
lines, make sure that the 135-volt connection 
to the B battery is taken off. Otherwise the 






FIG. 13 

The several ways in which the Ducon lamp-socket 
antenna may be connected to the receiver 



FIG. 14. AN ELABORATE PIECE OF RADIO 
FURNITURE 

A Jewett Highboy loud speaker-radio cabinet in 
which has been combined a loud speaker, a battery 
cabinet and receiver housing. The sliding doors 
have been so arranged that any standard-sized re- 
ceiver may be fitted within the housing. There is 
still ample room for the installation of a home-made 
or portable phonograph 



last section of the battery will be ruined. 
This is also shown in Fig. IO-A. 

The regeneration of volume of this receiver 
must be controlled smoothly, and we have 
found that much depends on the type of de- 
tector tube used. The 45 volts indicated in the 
diagrams is a very flexible standard, and various 
voltages from 8 to 90 h#ve been employed 
successfully with various tubes. The detector 
connection in Fig. 9 is therefore variable. 

CENTER HOLES ONLY 

TEMPLATES for drilling accompany all 
modern parts, and to avoid giving the im- 
pression that particular units must be em- 
ployed, we have merely indicated the center 
holes for condensers, coils, rheostats, jacks, 
and the filament switch mounting in the 
panel-layouts. 

MAKING A PORTABLE OF THE RADIO BROADCAST 
PHONOGRAPH RECEIVER 

IN FIG. 7, we illustrate a receiver which was 
made to fit in a console phonograph. By 
removing the entire unit from the console 



How to Build Radio Broadcast's Phonograph Receiver 



399 




FIG. l6 

The rear view of the Sonora cabinet illustrating 
the ample space which has been provided for the 
installation of even larger types of storage B 
battery. The removable back-panel is shown at 
the right of the main cabinet 



FIG. 15. A STANDARD FORM OF RADIO- 
PHONOGRAPH 

In this cabinet, manufactured by the Sonora 
Phonograph Company, has been built a 
Roberts four-tube receiver. The compart- 
ment underneath the receiver contains all the 
necessary batteries for its operation 

and placing it in a wooden carrying case, or 
other container, and using dry cell tubes we 
have an ideal portable for use on automobile 
trips, boat rides, and other summer activities. 




RADIO BROADCAST Photograph 



For use of this sort we have found that 
wo-12 tubes are very satisfactory and that 
either three or four standard dry cells con- 
nected in parallel work very nicely. If the 
receiver is not to be used as a portable for 
more than a few weeks, three dry cells will 
suffice, but for 'periods longer than a month 




RADIO BROADCAST Photograph 

FIG. 17. FLEXIBLE WIRING 

A receiver employing the new type of Como push-pull amplifying transformers. It will be seen 
from the photograph that direct wiring has been employed to connect the various units 



4<x> 



Radio Broadcast 





1 8. 



RADIO BROADCAST Photograph 



FIG. 18. THE SUB-PANEL 

Another view of the bottom of the sub-panel illustrat- 
ing the use of Jefferson push-pull transformers. The 
same make of audio transformer has been employed 
for the audio-reflex stage 

we recommend the use of four cells. The con- 
nections are shown in Fig. 10-8. The plate 
current drain with dry cell tubes is very low 
and for this reason the very small B batteries 
may be used. When operating the receiver 
about two hours a day, these batteries will 
last a month or more. There is room enough 
for the sky-scraper type, however, and they 
will last much longer and are more worth- 
while where weight is not the primary con- 
sideration. 

THE SUMMER TIME ANTENNA 

THERE are many methods for the provi- 
sion of antenna for use with this receiver 
in the open. No doubt there is a good market 
for an antenna made in the form of a reel, 
similar to a fishing reel. Several antenna 
reels have been brought to us in an unfinished 
condition, but we know of none now on the 
market. This type of radio specialty offers 
a very attractive field, and we believe that the 

FIG. 19. IN PLACE OF RECORDS 
Here is illustrated a method of mounting the RADIO 
BROADCAST Phonograph receiver unit in that part of 
a Victrola cabinet ordinarily used for the storage of 
phonograph records. Several shelves have been re- 
moved to make room for the unit and some shelves 
for records still remain. A loud speaker unit has been 
mounted on the tone arm thereby making use of the 
Victrola sound box mounted within the cabinet 



How to Build Radio Broadcast's Phonograph Receiver 



401 




RADIO BROADCAST Photograph 
FIG. 2O. THE CUSHION SOCKETS 

The photograph illustrates how the Benjamin spring cushion sockets may be mounted directly on the sub- 
panel. A manufactured unit of this type is being marketed by the Benjamin Company 



BRf 
H 

1- 


kCKET MOUNTING 

)LE *27 DRILL 
/ 
r 


BRACKET MOUNTING 
HOLE *ll DRILL*. 


T i T i \ / T^_j__j_j 


_t 
Tt 

r 


| 


| ir _L 7- ^L T" " BINDING POST/' 

16 4 ~ *~~8~" HOLES *27 DRILL 
in'" 


8 8" 


I 


-5" 



FIG. 21. THE BAKELITE BINDING POST LAYOUT 



COIL MOUNTING SOCKETS ON 2 BRACKETS MOUNTING 


HOLE *Z7 DRILL ^,- TOP OF BASE-^ HOLES Z7 DRILL'. 


t 


/' / ^. -^ .' 1 


Ml 


00 


-( 


>\.l 


/ 


X 


X 


f 1 


T 








TJ 


RADIO FRECcUENCY DETECTOR 


PUSH PULL 


PUSH PULL 







Ml 
f 


t> 

4 




if 


SOCKET SOCKET 


SOCKET 


SOCKET 




.1 

roio 











P 6J L P G 


[Pi G 


P 6 










^ 
1" 


> 


""5 NEUTRALIZING 1 GRID CONDENSER 
!__ _ *TCOND.ONTOP [. !^J~" UNDER BASE 






ir 


r j 


f ~ 


1 




1 ~* 


4 






"^4 


* 


yt BRACKET,' 
MOUNTING HOLES 
*Z7 DRILL 




^^TRANSFORMER , NpuT WSH wu 
UNDER. BASE TRANSFORMER. 


OUTPUT PUSH PULL 
TRANSFORMER 










UNDER, BASE. 


UNDER BASE 
















-. ... mL" 





FIG. 22. THE SUB-PANEL LAYOUT 
Showing how the parts, are placed underneath the base 



4O2 



Radio Broadcast 




FIG. 2 3 A-B. THE- MAIN PANEL 

And sub-base with most of the wiring completed. A circuit diagram is shown in Fig. 8. The numbered 
leads are connected to the following terminals; they may be traced directly to the apparatus in the Figure 
above. No. i goes to the single circuit inside jack. No. 2 connects to the outside filament circuit and double 
circuit jack. No. 3 goes to the ground lead and the switch arm. No. 4 leads to the antenna coil T-I. 
No. 5 connects to the inside secondary T-2 and to the rotary c-i. Nos. 6 and 7 go to the output jack, 
single circuit. No. 8 goes to the inside jack, double circuit. No. 9 to the outside jack, double circuit. No. 10 
goes to stationary plate 02 inside T-2 secondary. No. 1 1 goes to the N-P coil neutralizing condenser. No. 12 
connects to the tickler coil detector plate. No. 13 goes to stationary plate c-i and outside secondary T-I. 
No. 14 is connected directly to the tickler. No. 15, to the center tap N-P and No. 16 to N-P coil plate 

2 34 




16 



How to Build Radio Broadcast's Phonograph Receiver 403 




FIG. 24. THE MAIN PANEL LAYOUT 

Showing drill sizes and dimensions. No condenser mounting holes 
are indicated because this depends upon the type of condenser used 



404 



Radio Broadcast 




RADIO BROADCAST Photograph 
FIG. 25 

Shows a very fine addition to any radio and phono- 
graph combination. The use of th ephonograph 
horn for either radio or phonograph purposes may 
be had by turning the knob shown in the direct cen- 
ter of the illustration. The loud speaker unit is 
mounted upon the cap of the Selectron unit. The 
tone arm fits on the right side and the speaker unit 
on the left 

concern that will manufacture such an antenna 
will have no trouble in marketing this product. 

There are several other antenna devices 
for use in connection with electric light cir- 
cuits and telephone lines which make a regu- 
lar antenna unnecessary. Where there is a 
portable receiver and a small loud speaker 
at hand that may be put in the car, it is 
becoming increasingly popular for the radio 
enthusiast to take his "music box" with him 
when visiting friends. This makes com- 
parison of results obtained in various loca- 
tions with different types of receivers possible 
and frequently makes an otherwise boresome 
visit a really pleasant one. 

The antennaphone, which is illustrated in 
Fig. n, is a very simple device and is in no 
way connected to the telephone. It is laid 
on a table or other convenient place and the 
telephone is set down on it. This makes the 
use of a regular antenna unnecessary. 

The antenna attachments for use with the 
light sockets are illustrated in Fig. 12 and the 
various methods for employing them are il- 
lustrated in Fig. 13. It is impossible to 
tell in advance just which connection will be 
best. Each should be tried. Devices of this 
kind have been found of little value in some 
places but better than a regular antenna in 
others. Radio products of reliable manu- 
facture are sold on a money-back-guarantee 
basis. They are well worth trying for those 
whose problem of antenna erection is difficult 
and often impossible. 



ANY STANDARD PARTS MAY BE USED 

THERE is little necessity for reviewing the 
havoc caused by the new and novel fea- 
tures which have attracted the buying public 
from time to time. Buyers have spent large 
sums of money in the purchase of new equip- 
ment, spuriously advertised, only to find that 
their money had been grossly misspent and 
that their purchases were neither new nor 
revolutionary. Quite probably many in- 
dividuals have grown to think that the manu- 
facturers desired only to sell parts regardless 
of the satisfaction that they might otherwise 
give. 

After all, there is but one basis upon which a 
parts business can exist and that is to give the 
home builder at least some value for the 
money he has expended. 

For example, there once was heralded a 
revolutionary super-heterodyne which em- 
ployed nine tubes. As a result of the pub- 
licity it received many of the parts specified 
for use in it were sold to jobbers and dealers 
in comparatively large quantities. But it did 
not last long; it was too unreliable for that. 
As an example of its "efficiency" it consumed 
73 milliamperes in the plate circuit a good 
super-heterodyne should not use more than 
20, and many require much less the Hanscom 
six-tube receiver described in RADIO BROAD- 
CAST for June, 1924, for instance. Now, 73 
milliamperes means that dry cells are out of 
the question and even battery eliminators 
can not be used. There is then nothing left 
but storage B battery operation. When 
equally satisfactory results may be obtained 
and this is stating the case conservatively 
from one of the receivers employing the 
Roberts circuit and four tubes drawing less 
than 10 milliamperes, it is not difficult to 
understand what we are talking about when 
we say we are trying to show how good radio 
parts can be bought by the interested con- 
structor, and real service be secured from their 
use. 

RADIO BROADCAST'S Phonograph Receiver 
may be constructed by the use of any good 
standard parts, but we strongly oppose the 
use of parts which have not become stand- 
ard. 

After all, it is the consumer who eventually 
pays the piper and we can but hope that he, 
in making his purchase, will choose only those 
products which he knows to be sound. Even- 
tually this practice will lead to a market 
unencumbered by the "gyp" parasites which 
at times even now defile it. 



How to Build Radio Broadcast's Phonograph Receiver 405 





FIG. I, 



FIG. 2 





FIG. 3 



FIG. 4 



A CONNECTION CORD FOR OUTSIDE LEADS 

In the Phonograph receiver. Figs. 1 to 4 show the processes in preparing the wires for attaching at both ends. 
The cable, composed of two No. 16 and three No. 20 conductors is used to connect the batteries to the set. 
The conductors are each rubber insulated and each of a different color. First shirr the outer braid back about 
six or eight inches, or as far back as is necessary to make connections. Next fold the loose ends back over the 
cable and finish off neatly by wrapping a piece of half 'inch adhesive tape around the cable as shown in Fig. 2. 

With scissors, trim off the frayed edges as shown in Fig. 3. In pre- 
paring the individual conductors, skce the insulation at three or 
four points around the wire about one inch back, permitting the in- 
sulation to be removed very easily. The finished ends my be wrapped 
with a quarter-inch strip of adhesive tape for neatness. If some 
shellac is available, the ends might be dipped in it and dried before 
the insulation is removed. The copper wire should be scraped 
brightly and twisted tightly to prevent the wires from spreading. 
Fig. 5 shows one end of the completed lead. In the Phonograph 
Receiver, the top lead is plus B 120 volts, the next to the left is plus 
B 90 volts, the third plus B 45 volts, the next plus A, and the last 
minus A and B. This does not provide for C battery connections, 
which should be made with separate leads. The C battery itself 
can well be included inside the set. Considerable importance 
attaches to proper C battery potential in this receiver. This cord is 
available on the market as R-1360 and made by the Belden Manu' 
facturing Company. 





FIG. 5 



llllim iniMiniMnillllMIMIIinMinlllllMIIIIIMIIIMIIIIMIIMIIIIIUIIIIIIIIIIIIIMIIIMIMIinilinilMIIIIIIMIIIMMIMIIIIIinNIMMIMIMIIIMIIlllllllllMMIIIIIIIMIIIIIIIIIIMIIIMIIIIIIMIMIIIIIIlnilllllinn 



i 

i 



NO\X/ I HAVE FOUND ... ... I 

A Department Where Readers Can Exchange Ideas 
and Suggestions of Value to the Radio Construcfor andOperator I 

3 




FIG. I 



A FOUR TUBE ROBERTS RECEIVER 

THE outfit shown in the photograph, 
Fig. i. represents one of the highest 
types of receivers embodying the 
Roberts circuit. Of several hundred various 
Roberts sets made by the writer and Mr. S. 
Schneider, it was selected as the best of the 
lot as far as tone quality and ease of volume 
control were concerned. 

The feature of the set is its employment of 
a brace of Western Electric push-pull trans- 
formers removed from a y-A amplifier unit. 
The tapped input transformer is connected in 
the circuit as the reflex transformer, feeding 
the audio component of the detector plate 
current back into the grid circuit of the first 
tube. The secondary winding is the tapped 
one, there being five taps in all. The switch 
arm is connected to the positive side of the 
C battery, and the negative pole of the latter 
is then carried to the lower side of the antenna 
coupler secondary. 

The actual switch and contact points are 
mounted on the panel at the extreme left. 
They are not visible in the photograph because 
they are covered by the antenna coupler coils. 
This switch directly controls the volume ob- 
tainable from the receiver. 

The push-pull transformers are wired to a 
pair of 'tube sockets in the standard arrange- 



ment. These parts occupy the section of the 
baseboard to the right of the detector tube 
socket. 

Two automatic filament control jacks allow 
the use of either two or four tubes. Individual 
rheostats are provided on the panel for the 
r. f. and detector tubes, while another rheostat, 
screwed to the baseboard near the second 
phone jack, regulates the less critical audio 
bulbs. This thiid rheostat is turned to the 
best position for amplifier operation, and can 
then be entirely neglected. The filament 
jacks take care of all switching. 

The unusual transformer system does not 
alter the operating characteristics of the cir- 
cuit in the slightest. The set tunes exactly 
like other Roberts sets. 

In active service this receiver is truly a 
"knockout." It is being used by a resident 
of Washington Heights, New York City, and 
under the adverse local conditions has brought 
in Pacific Coast stations on only two tubes. 
The reproduction, thanks to the excellent 
transformers, is as perfect as the modulation 
of the broadcasting stations permits. The 
volume with uv-2oiA tubes, or others of 
similar constants, is more than sufficient for 
the large apartment in which the set is used. 
And the appearance, it might be stated, is 
quite commensurate with the electrical effi- 
ciency. H. Q. HORNEIJ, New York City. 



How to Make a Low Melting Point Solder 



407 




FIG. 2B 



A SIMPLE variable mounting for the 
antenna inductance of the Roberts 
receiver may be a practical suggestion 
which will interest the readers of RADIO 
BROADCAST. 

The several Figures are as follows : Fig. 2 A 
the assembled coils, cross section view; Fig. 2 B 
front view of secondary, unassembled; Fig. 2 C 
cross section view of antenna coil, unassem- 
bled. 

The blocks of wood which hold the coils are 
^ inch thick. The constructor may use his 
own judgment as to the width but i^ by i| 
by ^ inches has been found satisfactory for the 
secondary mounting and i by i^ by \ inch 
for the antenna mounting. 



Coils -. 




The base which supports the sliding second- 
ary and the stationary antenna coil is \ inch 
thick, i \ inches wide and 4 inches long. 

This base may be set back a distance from 
the panel, and the control rod cut to the 
proper length accordingly. 

The antenna coil is fastened to the block by 
small 'screws. This block is permanently 
fastened to the base. It has a hole drilled in 
it to allow the shaft which moves the second- 
ary to pass back and forth through it. 

With this arrangement, very fine variable 
coupling between the primary and secondary 
coils may be obtained. 

The sketches show very clearly the mechan- 
ical features involved in the construction of 
these mountings. H. BATCHELDER, Yakima, 
Washington. 




FIG. 2C 



HOW TO MAKE A LOW MELTING 
POINT SOLDER 



w: 



FIG. 2A 



HAT radio fan has not found, when 
soldering, that some of the work got 
so hot that either the appearance or 
utility of the soldered part was affected? 

While in many cases it may be true that 
sufficient experience would have allowed the 
constructor to avoid the trouble, still any 
method of soldering with less heat would be 
greatly appreciated by many of us. The 
answer is simple. Use solder that melts at a 



Radio Broadcast 



lower temperature than that ordinarily sold 
on the market. 

Solder is made of a mixture of lead and tin. 
Since tin is much more expensive than lead, 
the manufacturer is inclined to put in more 
lead and less tin. Probably no solder avail- 
able to the radio fan is more than half tin, 
in spite of the fact that the melting point of 
solder becomes lower and lower with the 
increase of tin until a combination of about 
three fourths tin is reached. Such solder, 
with a low melting point, is known as "soft 
solder." 

Soft solder may easily be made in the home 
by adding tin to ordinary solder. Small 
quantities of tin are available in every home 
in the form of ordinary tin-foil. One must 
notice that not all of the "tin-foil" is really 
made of tin. The genuine article may be 
recognized by its softness and bright finish. 
Tin-foil which comes around eatables will 
really be made of tin if it comes into direct 
contact with them. One may be certain that 
foil which is separated from the eatable by 
waxed paper is not pure tin and can not be 
used for this purpose. 

To get the tin into usable shape, put the 
foil into a metal cover, such as a baking powder 
can cover, and add to it about as much rosin, 
by bulk, as you have foil, and then heat over 
a gas stove or other fire. Stir with the end 
of a match stick. Presently the tin will ap- 
pear as a bright puddle with a lot of black 
dirt over it. 

Now, to make the extra soft solder, add to 
this tin, ordinary solder about equal in amount 
to the tin recovered from the foil and heat 
until the two melt together. 

The resulting compound may be left in the 
cover to be picked up by the soldering iron, 
or it may be made into "wire" solder either 
by pouring into a groove gouged out of a piece 
of wood or by pouring into a soda straw with 
the lower end pinched shut. 

By using a soldering iron just hot enough 




to cause the solder to flow freely when using 
this soft solder, work may be done with ap- 
preciably less heating than usual. 

This solder is not quite as strong as the 
ordinary solder, but, in radio work, joints are 
soldered for good electrical contact rather 
than for mechanical strength. G. D. ROBIN- 
SON, Annapolis, Maryland. 



7" 



o 
o 
o 
o 
o 
o 




FIG. 4 



B+ 
FIG. 3 

THE OSCILLATOR IN YOUR SUPER- 
HETERODYNE 

IT IS not the purpose of this article to extol 
the super-heterodyne but to show you 
how to make yours more efficient. By 
efficiency I mean output divided by input. It 
is obvious that with a given input we can in- 
crease the efficiency of a set by increasing the 
output. Or if with a smaller input the output 
is the same in both cases then we have in- 
creased the efficiency. The average radio lis- 
tener is more or less familiar with the action 
of a vacuum tube as an amplifier. He proba- 
bly has less understanding of the tube's action 
as a detector and unless he is a transmitting 
amateur he has practically no knowledge of an 
oscillator. 

There are several oscillating systems in 
popular favor with the amateur for transmit- 
ting purposes, but of these only one, the 
Hartley, is satisfactory as an oscillator in a 
super-heterodyne. There are three forms of 
the Hartley. The one shown in, Fig. 3 is used 
almost universally, and this is the one we are 
about to consider. 



How to Test Headphones 



409 



As a generator of alternating current this 
form of oscillator is above reproach. In fact 
it does that too well, for it generates a lot more 
current than we can possibly use, and in the 
matter of squeals it is almost as great an of- 
fender as those receivers we know as bloopers. 
This is perhaps the most serious charge that 
can be brought against it. Used in its present 
form it is not as efficient as it might be. 

Such an oscillator, with 5 volts filament 
supply and 90 volts plate supply, will draw 
about .025 amperes (25 milliamperes.) If we 
stop the tube from oscillating by short circuit- 
ing the grid coil, the plate current drops to 
6 or 7 milliamperes. 

If we cut the plate voltage down to 20 volts, 
the tube, oscillating, will draw about 5 milli- 
amperes. But 'this is not good enough. 

There is no advantage in using a 201 A tube 
as an oscillator. A uv-igg is suitable for all of 
our purposes. By using a uv-igg in the cir- 
cuit in Fig. 3, with 20 volts on the plate, the 
B battery drain will be but 3 milliamperes. 
This is better since we have also reduced our 
A battery current. A uv-igg can be used in 
the same set with uv-2oiA tubes by using a 
separate rheostat, or better an amperite. 

Fig. 4 is a form of Hartley oscillator in com- 
mon use among amateurs for transmftting 
purposes but there is nothing in particular to 
be gained by its use. 

A third form of Hartley oscillator is shown 
in Fig. 5. This is the ideal form for our pur- 
poses. The plate current for a uv-igg oscilla- 
tor with the constants shown, will be from 
.0001 to .00015 amperes (100 to 150 micro- 
amperes). If you are using 45 volts on the 
detector plate and do not want to provide a 
separate B battery connection for the oscilla- 
tor, you will have to use a somewhat lower re- 
sistance grid leak. This oscillator will give 
you all the output that you can use to advan- 
tage. However, it is not strong enough to 
radiate seriously and it will oscillate smoothly 



and evenly over the entire broadcasting wave- 
length range. 

A tube will often oscillate in this circuit 
when it will not in the first one shown here, 
because the filament emission is not great 
enough to sustain oscillations in the former. 

If the tube is stopped from oscillating in the 
circuit 'shown in Fig. 5 the plate current rises 
to about .4 milliamperes. If the filament emis- 
sion is great enough to supply a plate current 
of 0.2 milliamperes, it will oscillate in this 
circuit. 

The insertion of a grid leak and condenser 
at the point marked X in Fig. 3 will result in a 
greatly improved oscillator almost as good as 
that shown in Fig. 5. However, for those who 
already have a "super," it offers less changing 
in wiring and will do very nicely. 

There are several schemes for using the so- 
called first detector as an oscillator. Exam- 
ples of this are the second harmonic oscillating 
system and the Pressley method. I do not 
recommend any of these because the added 
impedence in the grid circuit of this first tube 
more than offsets any advantage gained by 
using this tube especially when a really good 
oscillator consumes only 60 milliamperes of 
A battery, and 1 5 microamperes of B battery, 
current. F. W. HUTTON, Woodhaven, New 
York. 



North 



1-Current 'On* Connections wrong 

2- - Off" 

3- "On" Connections OK 




Phone Phone 

FIGS. 6 AND 7 




B+20 



FIG. 5 



A PHONE CIRCUIT TEST 

IT IS quite commonly known that to insure 
long life to the permanent magnets of 
phones, the field produced by the plate 
current flowing through the phone windings 
should assist and not buck that set up by the 
permanent magnets. Relatively few experi- 
menters know how to determine which con- 
dition exists. 

The object of this article is to give an ex- 
perimental method for such determination 
involving no more elaborate apparatus than 



410 



Radio Broadcast 



a pocket-compass, which should, however, be 
fairly sensitive. No knowledge of electricity 
is needed, although of course it would help the 
operator understand the "why "of the method. 

First unscrew the cap from the receiver and 
remove the diaphragm (unless the receiver be 
of the Baldwin type which has a mica dia- 
phragm). The phones and compass should 
then be placed in the relative positions shown 
in Fig. 6, paying attention to the fact that the 
compass should be north of the receiver. The 
north-seeking pole should point toward the 
phone when brought near it. If such is not 
the case, the receiver should be revolved about 
the axis a-a^ bringing the other pole nearest 
the compass. 

The compass, which may be placed on a 
safety match box or anything not having iron 
or steel in its construction to facilitate move- 
ment, is then shifted to a position approx- 
imately as shown in Fig. 7. The exact spot 
is determined by finding where the needle 
starts to swing to its normal north-seeking 
position. Just before it has left the influence 
of the phone magnet, which is when further 
slight movement causes the needle to swing 
abruptly toward the north, the plate current 
should be allowed to flow through the phones, 
preferably when a strong signal is coming 
through. If the needle swings toward the 
phones, the fields are mutual and the con- 
nections correct. If the needle swings to the 
north, the phone connections to the plug 
or , the binding posts, whichever are used, 
should be reversed. The deflection will be 
slight but unmistakable. L. T. PHELAN, 
Washington, District of Columbia. 

TO- DAY, there is small necessity for "match- 
ing tubes". The fact is, for most pur- 
poses tubes are so similar in their character- 
istics that they may be considered as being 
matched. The notable exception is in the 
super-heterodyne, where juggling tubes around 
in the intermediate stages is usually neces- 
sary to secure satisfactory reception. Howl- 
ing, instability (uncontrollable oscillations 
with beat whistles) at normal plate voltages 
are evidence of poor or improperly balanced 
tubes in the intermediate amplifier. 




Potato 



ndicates 
Positive pole 



THERE are devices on the market for 
finding the polarity of an electric bat- 
tery. That is, to find out which is the 
negative pole and which is the positive pole. 
This is always necessary when connecting up 
an automobile or a radio battery or in making 
electrical experiments. But did you know 
that all this could be done with the aid of a 
common white potato? 

Choose a potato with nice white meat and 
shave off a section of skin about the size of a 
half dollar so that the inside is exposed. Then 
turn on the current from your source of elec- 
tricity and grasp one of the wires with bared 
ends in each hand. Touch the wire ends to 
the potato about | inch apart and watch the 
result. In a few seconds the potato under one 
of the wires will be found to turn a shade of 
green. The section of the potato which the 
other wire touches will remain clear and white. 
See Fig. 8. 

The wire causing the greenish hue on the 
potato is connected to the positive pole of the 
battery. Therefore the other wire must be 
connected to the negative pole. This exper- 
iment will not work on alternating current of 
the house lighting circuit. It is a good test, 
however for storage or dry batteries or small, 
direct current generators such as are found in 
cars and power boats. L. B. ROBBINS, Har- 
wich, Massachusetts. 



THE " Now I Have Found . . ." department in this magazine is planned to furnish an outlet for 
the many excellent ideas dealing with various features of radio construction and operation which 
reach our office. If you have an idea about a valuable and useful new circuit, some new device, or a 
construction or operating suggestion, we should like to have it. We do not want simple or obvious 
suggestions, and material to be acceptable for this department must offer something of definite value 
to the constructor; mere novelty is not desired. Payment from two to ten dollars will be made for 
every idea accepted. Manuscript should not be longer than 300 words and typewritten. An award 
of twenty-five dollars will be paid for the best article published in every three'month's period. 
Address your manuscript to this department, RADIO BROADCAST, Garden City, New York 



QUESTION*/ AND 




See the Announcement on Page 418 

QUERIES ANSWERED 



CAN A LOOP BE USED WITH ONE-TUBE SETS? 

P. B Canton, N. Y. 

WlLL YOU EXPLAIN THE MEANING OF WAVE- 
LENGTH? 

F. C. Lansing, Mich. 

HOW DOES THE HIGH-MU RECEIVER DIFFER FROM 
THE ROBERTS? 

E. L. J. Berkeley, Calif. 

HOW SHALL I BE GUIDED IN THE SELECTION OF 
A STORAGE BATTERY? 

A. M. Brooklyn, N. Y. 

Is THE FOUR-TUBE CRYSTAL REFLEX CIRCUIT IN 



THE JUNE, 1924, ISSUE OF RADIO BROADCAST 

CORRECT? 

J. N. T. San Antonio, Texas. 

WlLL YOU PUBLISH A CIRCUIT SHOWING A NEU- 
TRODYNE RECEIVER EMPLOYING PUSH-PULL AUDIO 
FREQUENCY AMPLIFICATION FOR THE LAST STAGE? 

L. J. T. Portland, Me. 

WHAT TOOLS ARE NECESSARY FOR GOOD RADIO 
CONSTRUCTION? 

K. W. J. Marion, Ohio. 

How MAY I PROCURE THE L.YNCH LEAD DE- 
SCRIBED IN THE JUNE, 1925, RADIO BROADCAST 
R. B. Albany, N. Y. 



THE energy transmitted by a broadcasting 
station must be collected or absorbed by 
some collective or absorbing agency so that 
a receiver may be actuated to produce results. 
Upon the size of this agency depends the efficiency 
at which the receiver operates, all other things 
being equal. However, this agency, which is the 
antenna, also is affected by other electrical disturb- 
ances in the ether, i. e., atmospherics, artificial 
static like motor commutator sparking, sparking 
trolley lines, defective power lines, and similar 
disturbances. 

On one-, two-, and three-tube sets, an outside 
antenna is connected to the detector tube through a 
coupler unit. A loop will not be satisfactory for 
such a receiver because the feeble impulses which 
it receives will not actuate the detector tube suf- 
ficiently to produce energy which may be trans- 
formed into an audible signal. 

A loop can only be used on receivers employing 
one or more stages of radio frequency amplification 
or in super-heterodynes which tend to magnify 
these feebly received impulses so that they are 
strong enough to be heard after being rectified to 
an audible signal in the detector tube. 

While an antenna has directional effects, it is 
not practicable to move it about so that signals from 
all directions may be received with comparatively 
equal strength. 



A loop can be rotated without much effort, for 
directional effects. The larger, physically, a loop is 
the greater its energy pickup will be. However, for 
most practical purposes its size is limited by indi- 
vidual requirements, 
then we have the equation 

WHAT WAVELENGTH MEANS 

RADIO waves travel through space at the 
same velocity as light, roughly 186,000 miles 
per second. Rather, the wave motion is 
propagated at that velocity, which, when spoken 
of in meters equals 300,000,000 meters per second. 
That is a fixed value. Now if we vary the length of 
one wave, the frequency or number of times it will 
repeat itself, will vary. As represented in a formula 

186,000 miles (300,000,000 meters) 

Frequency = 

length of wave 

If N equals the frequency or number of oscillations 
occurring, V (300,000,000) indicates velocity of 
waves in meters, and L equals length of wave form 
then we have the equation. 

V 

v = 

L 

L, the length of one wave depends upon the ad- 
justments of the tuning elements to produce an 
oscillation which repeats itself in a propagated wave 



412 



Radio Broadcast 



form at a certain frequency. We can term this the 
number of oscillations produced by an adjustment 
which gives each oscillation a definite length in 
meters. 

Reduced the formula is 



To deal with round numbers let us suppose we start 
with a wave i meter long. Then the number oi 
oscillations (waves or cycles) occurring during the 
one second it takes to travel 186,000 miles (or 
300,000,000 meters) is exactly 300,000,000. 

Supposing we wish to determine the frequency 
(N) of a wave 600 meters in length then 



N = 



300,000,000 

= 500,000 oscillations 

600 



If it is a wave 300 meters long then 

300,000,000 

N = = 1,000,000 oscillations 

300 

If it is a wave 150 meters long then 

300,000,000 

N = = 2,000,000 oscillations 

150 

Therefore from this we can judge that while the 
speed at which the wave travels remains constant, 
any change in wavelength will alter the number of 
oscillations (waves) occurring over that distance of 
186,000 miles. This is explained in Fig. i A, B.andC. 




1*600* - 
one cycle 



600 METERS 
500,000 cycles per second 



300 METERS 
1,000,000 cycles per sec 



150 METERS 
2,000,000 cycles per sec 




186,000 miles 
one second of time 

FIG. I 



Since the space covered by the wave forms is 
186,000 miles then for each one there occurs a dif- 
ferent number of waves in that space. 

Assuming that the same power is used in all three 
cases to produce the same amplitude then in A 
(600 meters) there will be 500,000 oscillations or 
cycles each 600 meters long from start to finish. 
In B there will be 1,000,000 and in C there will be 
2,600,000, 



Summing up we can say that the length of one 
cycle determines the number of cycles occurring 
during one second of time or covering 186,000 
miles. 

In broadcasting, a station transmits a wave called 
the carrier wave, which has a constant amplitude. 
This wave, occurring at a frequency to which the 
transmitter has been adjusted, is inaudible to the 
ear. Now by super-imposing an audio frequency 
wave on it, it is modulated into varying amplitudes 
but still inaudible until rectified by the detector 
tube. 




FIG. 2 



Fig. 2 shows how the modulated wave, to conform 
to the voice and music variations, is produced. At 
A we have the constant amplitude of the carrier 
wave but between A and C (B) the wave is of a con- 
tinually varying amplitude. This is due to the 
audio wave being super-imposed on the carrier 
wave. 



THE HIGH MU AND THE ROBERTS 

THE question arises "how does the High-Mu 
Browning-Drake receiver differ from the 
Roberts Knockout?" Well fundamentally 
both circuits are similar, each employing a stage of 
radio frequency amplification before a regenerative 
detector circuit. However, in the Roberts Knock- 
out, the first tube circuit contains a reflex audio 
transformer providing an additional stage of audio 
amplification. Also, the neutralization methods 
are not alike. The novel Roberts system is quite 
different in principle to that employed in the High- 
Mu receiver which is similar to the standard 
Hazeltine neutralizing scheme. 

The High-Mu receiver was designed for use with 
uv-i99 tubes but uv-2oiA*s may be employed 
without any changes other than supplying the 
correct filament and plate voltages. This is borne 
out in the description of the "Good Fpiir Tube 
Receiver" in this magazine for March, 1925, which 
is very similar to both the Roberts and High-Mu 
sets. 



HOW TO SELECT A STORAGE BATTERY 

WHEN selecting a storage battery, every 
owner of a receiving set desires one of suffi- 
cient capacity to make frequent recharging 
unnecessary, yet small enough to reduce the first 
cost to a minimum. The owner's ideas about what 



RADIO BROADCAST ADVERTISER 



413 



US1C 

. jcisier 

Resonant Wood 

Insures 

Natural 

Tone 

Quality 




Model VI, 14" Wood Bell 
Model VIL 21" Wood Bell 




Connect Music Master 
in place of headphones. 

No batteries. 
No adjustments. 

Prices of all models 

slightly higher 

in Canada. 



^^ 

Music Master Makes 

set BETTER 

Music Master transforms mere radio reproduction 
into artistic re-creation. Mere assertion? No! Plain 
fact because : 

THE piano's sound board, the violin and 'cello, and Music 
Master's amplifying bell are all of wood because wood pro- 
duces natural tones. 

Heavy cast aluminum eliminates over-vibration, develops sound 
without distortion and imparts a unique tonal brilliance. 
This balance of resonant wood and non-resonant metal preserves, 
reproduces and re-creates the natural qualities of instrument and 
voice and makes 

Music Master the Supreme Musical Instrument 

of Radio, for which there IS no substitute. 

Buy Music Master and be safe buy Music Master and improve 

your set buy Music Master and exchange mere radio receiving 

for the artistic enjoyment of radio re-creation. 



kfodel VIII, Mahogany Cab!- Model V, Metal Cabinet, 
net with full-floating $1 C Mahogany Finish, XI O 
Wood BejJ . ...... JJ Wood Bell . . . . , J-O 



Makers and Distributors of High-Qrade Radio Apparatus 

Tenth and Cherry Streets 

Chicago PHILADELPHIA Pittsburgh 

Canadian Factory : Kitchener, Ontario 






RADIO 



REPRODUCER 



414 



Radio Broadcast 



to specify, in order 
to obtain this high- 
ly desirable com- 
bination maybe 
somewhat hazy, 
but he is never in 
doubt as to the 
result he seeks. 

Various types of 
storage battery 
selection charts 
have been de- 
veloped in the 
past, which were 
intended to assist 
the owner of a re- 
ceiving set in mak- 
ing a proper 
selection. Gener- 
ally speaking, these 
charts recom- 
mended certain 
types and capaci- 
ties of batteries 
for certain tubes. 
The Prest-O-Lite 
Storage Battery 
Laboratories have 
just developed a 
chart which takes 
into consideration 
the numbers, types, 
and combinations 
of tubes in a way 
that makes the 
selection of a satisfactory battery a simple matter. 

Voltage of tubes, number of tubes, type of tubes, 
the rated ampere drain and the recharging interval 
are treated in the chart in such a way that the receiv- 
ing set owner has a choice of two recharging periods. 
For instance, for a set using one uv-2oo and three 
uv-aoiA tubes, with a rated ampere drain of if, and 
an A battery of 115 amperes (at a one ampere 



Voltage 
of 

Tubes 


No. 

Tubes 
In Set 


Type 
of 

Tubes 
(see foot-note) 


Total 
Rated 
Ampere 
Drain 


Storage "A" Battery 
Size 
Recommended 


Amp. Hours 
at 1 Amp. 
Drain 


Days 
between 
Charging* 


5-Volt 
Tubes 

C-300 and UV-200 
are interchange- 
able 

C-301A, DV-2and 
UV-201A are in- 
terchangeable 

Copyright, 1925 
The Prest-O-Lite Co..Inc 


1 


UV-200 


1 


65 


22 


47 


16 


2 


UV-201A 


J-2 


47 


33 


2 


1 UV-200 
1 UV-20IA 


IK 


80 


22 


65 


17 


3 


UV-201A 


K 


65 


29 


47 


22 


3 


1 UV-200 
2UV-20IA 


IK 


95 


21 


65 


14 


4 


UV-201A 


1 


65 


22 


47 


16 


4 


1 UV-200 
3 UV-20IA 


Wi 


115 


22 


80 


15 


5 


UV-201A 


IX 


SO 
65 


22 


17 


S 


I UV-200 
4UV-201A 


2 


115 


19 


80 


13 


6 


UV-201A 


IK 


95 


21 


65 


14 


8 


UV-20IA 


2 


125 


21 


95 


15 


For sets using cur- 
rent at a rate higher 
than 2 amperes. 


2K 


140 
95 


22 


13 


2K 


140 


19 


125 


16 


For combinations of tubes not listed: Use the same battery combinations recommended 
for tubes having voltage and current requirements similar to the tubes ydu have. 

NOTE: If you use a loud speaker operated from your "A" Battery, add Yt ampere to 
the total rated current drain of your tubes and then select a battery giving this total 
current consumption. 



drain) will give 22 
days of service 
without recharging 
when used daily 
for an average of 
three hours; while 
with the same tube 
combination, a 
battery of 80 am- 
peres will have a 
recharging interval 
of 1 5 days. Simi- 
larly, for a set hav- 
ing three uv-2oiA 
tubes at a f -ampere 
drain, a battery of 
65 amperes insures 
29 days of service 
while the smaller 
47-ampere battery 
gives 22 days of 
service between 
rechargings. 

By recalling at- 
tention to the types 
of tubes that are 
interchangeable, it 
will be noted that 
the accompanying 
chart, Fig. 3, gives 
practically every 
combination of 5- 
volt tubes in gen- 
eral use. 



CORRECTIONS IN THE FOUR-TUBE CRYSTAL REFLEX 
RECEIVER 

IN QUESTIONING the accuracy of the four- 
tube Knockout crystal reflex circuit appearing 
in Fig. 3 page 103 of the June, 1924, issue of 
RADIO BROADCAST and also in Fig. 3 page 41 of our 
Knockout Series Booklet, it has been brought to our 




4r ? 

-o +o o- 04- o+ 120 



"A' "B"90 



FIG. 4 



RADIO BROADCAST ADVERTISER 



415 



Stations 
Don't Bunch 
On the Dials 



CONDENSERS 







The location of the -| 
same stations on the 
same dial using Ultra- 
LowLoss Condensers 
" spread ", simplifying 
tuning. 












.0005 mfd 



PATENT PENDING 











tlLTR^-VSRHISR 

TUNING CONTROL 

Simplifies radio tuning. Pen- 
cil record a station on the 
dial thereafter, simply turn 
the finder to your pencil 
mark and you get that station 
instantly. Easy quick to 
mount. Eliminates fumbling, 
guessing. A single vernier 
control, gear ratio 20 to 1. 
Furnished clockwise or anti- 
clockwise in gold or silver 
finish. 

Silver $2.50 
Gold $3.50 




Tuning Simplified Novt f 

The day of tedious fumbling about for your stations is past 
science has been brought into play. Now, with the Ultra- 
LowLoss Condenser you can instantly tune in on any station 
as easy as turning the hands of a clock to the hour. 

With one station of known wavelength located on the dial, all others 
can be found instantly. Each degree on a 100 degree dial represents 
approximately 3% meters difference in wave length. This applies to 
both high and low wavelengths. Other than 100 degree dials vary ac- 
cordingly, l 
This simplification of tuning is made possible by the new Gutless Stator 
Plates to be found only in the Ultra-LowLoss Condensers. Every fea- 
ture of the Ultra-LowLoss Condenser was developed with one predomi- 
nating purpose to overcome losses common in other condensers. De- 
signed by R. E. Lacault, originator of the famous Ultradyne Receivers 
and Ultra- Vernier Tuning Controls. 

At your dealers, otherwise send purchase price and you will be supplied postpaid. 
Design of lowloss coils furnished with each condenser for amateur and 
broadcast wavelengths showing which will function most efficiently with 
the condenser. 

TO MANUFACTURERS WHO WISH TO IMPROVE THEIR SETS 
Mr. Lacault will gladly consult with any manufacturer regarding the application 
of this condenser to his circuit for obtaining best possible efficiency. 



CONDENSER 

PHENIX RADIO CORPORATION 116-C East 25th Street, New York City 



Tested and approved bv RADIO BROADCAST 



416 



Radio Broadcast 



1ST.R.F. STAGE 



2ND.R.F. STAGE DETECTOR 

,C 9 



1ST AF. STAGE 2NDAF. STAGE 

(Push-Pull Amplification) 




FIG. 5 



attention that in its present form the A battery 
would short-circuit itself through the rheostat Ry 
when that rheostat is turned on. The defect in the 
circuit diagram is in making the connection of the 
lower side of Ra to k that lead of the filament circuit 
connecting to the upper end of the rheostat Ry. 

The correct connection should be made to the 
line just below where the connection is now made, 
or in other words, to that lead running from the left 
hand side of each of the filaments of the first two 
tubes. 

The corrected circuit diagram appears in Fig. 4. 

A NEUTRODYNE CIRCUIT 

MR. D. C. asks for a neutrodyne circuit em- 
ploying a push-pull amplifier as the second 
audio stage. The complete circuit is shown 
in Fig. 5. 

The values of the various parts are: 

Ri, RJ, R3, R6, and Rj ao-ohm Rheostats 

R4 3-megohm grid leak. 

Rj Variable resistance 25,000 to 100,000 ohms. 

Cb C Battery 45 to 9 volts. 

Ci, C2,. 3 Variable condensers .00035 mfds. 

C4 Grid condenser .00025 mfds. 

C5 Stabilizing condenser .0005 mfds. 

C6, Cy Bypass condensers .006 mfds. 

C8, 9 Neutralizing condensers. 

The several radio frequency coil units consist of 
primary and secondary coils wound on 35 inch bake- 
lite or cardboard tubing. The secondaries are 
wound with 60 turns of No. 22 DCC wire and the 
primaries, situated at the lower end of the coil, that 
is, the end which connects to the negative side of the 
filament, consist of about 6 to 10 turns of the same 
wire. 

Any standard neutralizing condenser may be em- 
ployed. 

Information relative to the proper neutralization 
and to the operation of push-pull amplifiers has ap- 
peared in past issues of RADIO BROADCAST. 

RADIO TOOLS 

THE need for good tools in radio construction 
is paramount where one wants good work to 
result. The ordinary tools usually to be 
found around the house are not of very much use. 



The well-planned radio kit should contain: 
2 screw drivers one with \ inch and another with 
T\ inch blade, 
pair of wire cutting pliers. 
" " side 
" " duck bill 

round nose 
centerpunch 
ball peen hammer 
scriber 

adjustable square 
6-inch scale 
pair dividers 
set of socket wrenches 
soldering iron 
hand drill and set of drills 
Countersink 
Brace and wood bits 

The scale, square, scriber, centerpunch, hammer, 
etc., all aid in the laying out and marking of panels, 
brass and other work, while the hand drill, drills, 
countersink, etc., are used to do the actual work in 
the drilling of these materials. Round nose pliers 
are indispensable for bus wire bending and duckbill 
pliers may be handy for loosening and tightening 
nuts, bolts, etc. Side cutting pliers are usually 
employed for cutting wire and stripping off insula- 
tion. 

In the use of drills special care should be used 
when large holes are drilled. It is much easier to 
drill a |-inch hole by first using a No. 28 drill in a 
hand drill and then enlarging it by redrilling with a 
^-inch drill inserted in the chuck of a brace, than 
to drill with a |-inch drill at the very beginning. 
Furthermore, this practice tends toward accurate 
drilling because the point of a larger drill becomes 
displaced from the centermark easier than a small 
drill. 

A set of socket wrenches or ordinary S wrenches 
helps the constructor greatly in insuring secure 
assembly work. It is well to remember that not 
too much strain should be placed upon nuts and 
bolts because, due to their soft brass composition, 
it is easy to strip the threads. 

Every constructor ought to have an ample supply 
of bus wire, lugs, nuts, bolts, washers, and wood 
screws. 



RADIO BROADCAST ADVERTISER 



EVEREADY HOUR 

EVERY TUESDAY 

AT 8 P. M. 

(Eastern Standard Time) 
For real radio enjoyment 
tune in the "Eveready 
Group." Broadcast through 
stations 

New York 
Providence 
Boston 
Philadelphia 
Buffalo 
Pittsburgh 
Cleveland 
Cincinnati 
.Detroit 
I Minneapolis 
\ st. Paul 
WOC Davenport 



WEAF 

WJAR 

WE El 

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a good _ set - 
and Evereadys 

To ENJOY radio for the rest of your life, get the best 
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made by reputable manufacturers; it isn't necessary 
for anyone to get 'round-the-corner, unproved, un- 
reliable merchandise at any price. That applies 
to batteries too. Eveready Radio Batteries are made 
in so many sizes and prices that there is a correct, 
long-lasting Eveready for every receiver and for 
every radio home, ship or commercial station. Specify 
Evereadys for your new radio set. It is false economy 
to buy nondescript batteries at any time. In the long 
run you'll find it most economical to buy either the 
large or extra large Evereadys. Always buy Ever- 
eadys and enjoy the knowledge that no one can get 
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Tested and approved by RADIO BROADCAST 



4i8 



Radio Broadcast 



The following is a suggested list of what the supply 
should be: 



Bolts Round SIZE 

and Flat Head No. A 
(Brass) No. A 

Nuts (Hexa- No. A & A 
gon Brass) 

Wood Screws No. 3 

Round Flat 
& Oval Head 

(Brass or 
Nickel Plated)No. 5 |"-i 

Washers size to fit screws 



// _ 3H // 



tn \n atf 
"2 "4 



LONG CORDS 

INQUIRIES have been received asking where the 
1 Lynch Lead may be procured. This lead, des- 
cribed in the June 1925 issue of RADIO BROADCAST 
and illustrated in the frontispiece of this issue of 
RADIO BROADCAST, making possible the use of an 
automobile storage battery by plugging in to the 
lamp socket on the dashboard of a car is manu- 
factured by the Belden Manufacturing Company, 
Chicago, Illinois, and the Crescent Braid Com- 
pany, Providence, Rhode Island. 

The extra length loudspeaker cord also illustrated 
in the frontispiece of this issue may be obtained 
from the Alden Manufacturing Company, Spring- 
field, Massachusetts. 



Before You Write to the Grid 

THOUSANDS of you are writing the Grid for technical advice every month. The 
expense of framing a complete and exhaustive reply to each letter is very high. The edi' 
tors have decided that the benefit of the questions and answers service will continue to be 
extended to regular subscribers, but that non'subscribers, from April 15, on, will be charged 
a fee of $1 for each letter of inquiry which they send to our technical department. Very 
frequently, our technical information service proves of definite money value to you who 
write us, for we are often able by a sentence or two of explanation, to put you on the right 
path before you have made a perhaps expensive mistake. 

The occasional reader of RADIO BROADCAST will be charged a fee of $1 for complete 
reply to his questions, and the regular subscriber can continue to take advantage of the 
service as before. In that way the non'subscriber will help share the cost of the technical 
staff whose service he gets. Every letter receives the benefit of the experience of the editor 
and the technical staff and every correspondent may be sure that his questions will receive 
careful consideration and reply. 

When writing to the Grid, please use the blank printed below. 



GRID INQUIRY BLANK 
Editor, The Grid, 

RADIO BROADCAST, 

Garden City, }^ew Tor\. 
Dear Sir: 

Attached please find a sheet containing questions upon which \indly give me fullest 
possible information. I enclose a stamped return envelope. 

(Chec\ the proper square} 

O I am a subscriber to RADIO BROADCAST. Information is to be supplied to me free 
of charge. 

EH I am not a subscriber. I enclose $1 to cover costs of a letter answering my questions. 

My name is 

My address is. : 



>\ 



The $1.50 Ducon 



and no antenna! 





A small Ducon screwed into a light socket 
or a cumbersome, unsightly aerial? Surely 
the Ducon! It's so inexpensive so easy to 
use so sure in its results. 

Take home a Ducon to-day and hear to- 
night's best programs! 

The Ducon is sold by all reliable dealers. Try one 
for five days. If it is not thoroughly satisfactory, 
your money will be refunded. 



Dubilier 

CONDENSER AND RADIO CORPORATION 



Tested and approved by RADIO BROADCAST 



New Equipment 




ERLA RHEOSTAT 

Designed to require a min- 
imum of room behind the 
panel and yet it does not 
sacrifice the good qualities 
of larger rheostats. The 
split contact arm facilitates 
its operation over the re- 
sistance winding. It is 
secured to the panel by a 
one-hole mounting, a con- 
structional feature now This battery charger is one of those units employing a Tungar rectifying tube. It does its 
becoming quite popular, work very well, whether it is charging A batteries or high voltage B batteries. The unit is corn- 
Made by the Electrical posed of the necessary transformer and connections so that it may be connected directly to the 
Research Laboratorties, power mains. Made by the Acme Electric and Manufacturing Company, Cleveland, Ohio 
2505 Cottage Grove Ave., 
Chicago, Illinois 



ACME BATTERY CHARGER 




BRADLEYDENSER 

This interesting condenser 
is manufactured by the 
makers of the well-known 
Bradleystats. It is equipped 
with a brass shield designed 
to keep dust from the plates. 
Dust particles that become 
damp or electrically charged 
are responsible for much of 
the "swishing" noise that 
takes place when receivers 
are tuned. The condenser 
has a minimum of dielectric, 
low resistance plates and a 
smooth action 




HERCULES AERIAL MAST 

The above illustration shows how an efficient and 
good looking mast may be erected for your antenna. 
S. W. Hull and Company, 2048 East 79th St. 
Cleveland, Ohio, make these masts in three standard 
lengths 20ft., 40 ft., and 60ft., all steel construction. 
They are of a special angle construction that gives 
great strength and light weight, each of which is a 
decided advantage. When erected these masts 
will stand a five hundred-pound pull at the top 




SANGAMO FIXED 
CONDENSERS 

These condensers, made by 
the Sangamo Electric Com- 
pany of Springfield, Illinois, 
makers of the well known 
Sangamo meters, are a distinct 
addition to the condenser 
market. They may be 

thrown on a cement floor 
without breaking, heated 
with a soldering iron without 
changing their capacity, and 
soaked in water without ab- 
sorbing moisture. Their 
capacity is indeed "fixed" 



RADIO BROADCAST ADVERTISER 



44 





Vital to every radio fan 

In a radio set, it is the tube that detects the 
sound that amplifies the sound that deter- 
mines in large part the quality and volume of 
the sound. Therefore the tube intricate of 
mechanism and delicate to make is the vital 
spot in every set And it always pays to be 
sure you use genuine Radiotrons made with 
experienced precision. 

Build any circuit simple or complex. Buy 
any set, plain or fancy, simply boxed or elab- 
orately cabineted. But give it every chance 
to achieve its best with genuine Radiotrons. 
Be just as careful when you replace tubes, too. 
Ahuays see for yourself that each one bears the 
identifying marks of a Radiotron: The word 
Radiotron and the RCA mark. 



Radio Corporation of America 



Chicago 



New York 



San Francisco 



Radiotr 



PRODUCED ONLY BY RCA 



Tested and approved by RADIO BROADCAST 





"i noiinii nmini ginn i inimin Hiiniiiiiiiiii>ni mm m in man :;. ! i itraii mi 



THE SOCIAL SIDE OF RADIO 

Mrs. Dr. Elliott Norton, center, Frances Peralta, soprano of the Metropolitan Opera 
Company, right, and Mrs. Alberta N. Burton, at a radio set during the tea-hour. Women 
throughout the country are finding that they may hear delightful tea and dinner music 
during the late afternoon and evening, and a radio concert, given by a good 
orchestra, often adds to the pleasure of a cup of tea 



, :r ,'T Illllini!! tllllllllll III II IIIIIIIIIIIIIIIIIHIIIIIIIIIIII 



iiiiiiiiiiiiiiiiniiiiiiiiiiiniiini 



RADIO 
BROADCAST 



Vol. 7, No. 4 







August, 1925 



/ 



From Figures to Fame 

; 

Professor Louis Alan Hazeltine Finds that the Algebraic Un- 
known Quantity, X, Equals Fame, Fortune, and the Neutrodyne 



BY MYRA MAY 

ELDOM, if ever, would any one select s y tricate problems of the higher branch. And 
algebra as a sure road to fortune, so the unknown quantity, X, may, after all, 

be the Fame and 
Fortune of your 
dreams as well as 
the solution to your 
involved algebraic 
equation, 
dom that 



c 

jl While plumb- 
S*^ ing, banking, 
advertising, physics 
and every kind of 
concentration are 
glaringly depicted as 
a part of the curricu- 
lum of most corres- 
pondence school 
courses, it is exceed- 
ingly unlikely that 
these confident ad- 
vertisers would in- 
dicate algebra as the 
one path through 
which one might at- 
tain to Fame and 
Fortune that vision- 
ary goal of one's 
dreams. But it has 
been demonstrated 
that algebra and 
Fame and Fortune 
are somewhat synon- 
ymous and that one 
gains experience from 
the one branch of 
mathematics that 
helps to solve the in- 




PROFESSOR LOUIS ALAN HAZELTINE 

Inventor of the neutrodyne circuit, embodied in 
thousands of receivers used all over this country and 
abroad. Mr. Hazeltine is head of the Department 
of Electrical Engineering at Stevens Institute of 
Technology at Hoboken, New Jersey, and is here 
shown using a wavemeter in his laboratory 



It is sel- 
one gains 
Fame and Fortune 
through the direct 
application of mathe- 
matics, however, and, 
student or scholar, he 
is fortunate, indeed, 
who, having solved 
his algebraic problem, 
finds that the X, lit- 
erally spells Fortune 
itself. Such was the 
case with Louis Alan 
Hazeltine, inventor 
of the "neutrodyne" 
circuit. 

If someone were to 
ask you why radio 
interested you, you 
might reply that you 
liked to try for dis- 
tance, or that you 
enjoyed the enter- 



452 



Radio Broadcast 



tainment that a full program affords, or 
you might, like Professor Hazeltine, answer 
that it is the science of radio which interests 
you. Professor Hazeltine explains that it 
was the opportunity to work out mathematical 
problems that first led him to experiment 
with radio. He has never been especially 
interested in either the programs of broad- 
casting stations or in attempts to receive long 
distances. He has been concerned with little 
but the scientific side of wireless. It is char- 
acteristic of the man that he did not have a 
neutrodyne set himself until several years 
after he had worked out the fundamental 
theory mathematically and had made appli- 
cation for his patents. 

PROFESSOR HAZELTINE LIKES MATHEMATICS 

MATHEMATICS has always been a fa- 
vorite of mine," he says. "At school 
I once received a prize for my good work 
and my highest grades were always in mathe- 
matics. By chance, I graduated first in my 
class, but that was only by chance, for I had 
consistently held second place until the 
leader went to live in ahpther city. From a 
high school in New London, Connecticut, I 
transferred to Stevens Institut&-of Technology 
where in 1906 I graduated with the degree 
of Mechanical Engineer." 

Professor Hazeltine is too modest .to tell 
that he finished his school and college course 
in twelve years instead of the sixteen most 
of us give to it. He prefers to let people find 
that out for themselves. 

"I remember," he reminisces, "when I was 
a little boy I saw my uncle working out some 
algebraic calculations: he explained that he 
made those queer hieroglyphics just for 
amusement. 1 marvelled at such a pastime 
when there were such sports as baseball and 
swimming to claim spare hours. I had no 
premonition that some day I, too, would 
devote my leisure to the same queer hiero- 
glyphics. 

"When I entered Stevens Institute I did 
not know what branch of engineering I 
wanted to take up, but I did know that I had 
a prejudice against electrical engineering. 
Nevertheless, near the end of my course I 
began to feel that the performance of elec- 
trical apparatus could be predetermined 
more accurately than that of mechanical. It 
was this feeling that led me to change my 
field to electrical engineering in spite of 
my former prejudices, and later, it was this 
same feeling that led me to specialize in radio." 

After graduating from Stevens Institute, 



Professor Hazeltine entered the testing de- 
partment of the General Electric Company 
in Schenectady where he received a practical 
training. This was his only venture along 
the highroad of business, for the following 
year he was offered a position as assistant in 
the Department of Electrical Engineering 
at Stevens Institute and he has remained 
at that college ever since. 

WHY HAZELTINE SPECIALIZED IN RADIO 

1WAS fortunate in my surroundings at 
Stevens," says Professor Hazeltine, "for 
my work covered all branches of electrical 
engineering and the head of the department, 
Professor Albert F. Ganz, was always aiding 
and inspiring my further progress. During 
this period I specialized in one branch of 
electrical engineering after another, and pre- 
pared much of the material for presentation 
to my classes. It was in this manner that 
I gradually developed a text on electrical 
engineering, which has but recently been pub- 
lished. 

"Professor Ganz was the foremost author- 
ity in this country on the subject of electro- 
lytic corrosion of underground structures by 
stray electric current, particularly from elec- 
tric railways. At times I assisted him in 
this work and for several years after his death 
I was associated with the firm of Albert F. 
Ganz, Incorporated, which .continued ^ his 
professional work in electrolysis.". 

During the winter of 1914-1915, the well- 
known radio experimenter, E. H. Armstrong, 
wrote a paper, presented before the Institute 
of Radio Engineers, on the fundamentals of 
the three-electrode vacuum tube and then in a 
subsequent paper described in detail the tube's 
capabilities for oscillating which he had dis- 
covered. The young instructor at Stevens, 
who had always been partial to any branch of 
mathematical science, found a new and delight- 
ful field before him. Here at last was a real 
opportunity to apply mathematical analysis. 

THEORY PRECEDES PRACTISE 

LONG before Professor Hazeltine had one 
of the desired vacuum tubes he began a 
theoretical study of its operation, and it was 
in this manner that he worked out the theoret- 
ical requisite for the production of oscilla- 
tions. Not until then did he obtain a vacuum 
tube (then known as an audion) to trace its 
characteristic curve. On the basis of that 
information he designed his circuit, wired it, 
and immediately obtained the anticipated 
result. 



From Figures to Fame 



45? 




TWO RECEIVERS 

Designed by Professor Hazeltine. The one in the insert was designed for the Navy Department during 
the war and is known officially as the SE 1420. It was while he was developing this .receiver that the idea 
for the neutrodyne circuit was partially evolved. The larger photograph shows Mr. Hazeltine and one of 

his models of the neutrodyne 



In spite of this remarkable performance, 
Professor Hazeltine continued his theoretical 
studies coupled with experimental verifica- 
tions for the next two years, and it was not 
until 1917 that he felt that his work was in 
sufficiently perfect form to give it to the 
world. His paper on "Oscillating Audion 
Circuits" which gave the results of his in- 
vestigations was read before the Institute of 
Radio Engineers. This was the first time that 
a general and yet a simple mathematical 
method for the treatment of oscillating au- 
dion circuits had been given. It was in this 
paper that Professor Hazeltine used the ex- 
pression "mutual conductance," a term that 
has since become as much a part of radio 
language as have antennas and batteries. 
Professor Hazeltine asserts that all of his 
subsequent radio work and whatever success 



he has achieved may be traced to that pa- 
per. 

Wireless was claiming more and more of 
Professor Hazeltine's time. The following 
summer he devoted to experimental work in 
radio telegraphy and telephony in conjunc- 
tion with Mr. Paul Ware. Later Mr. Ware 
joined the Signal Corps of the United States 
Army where he continued his research and 
produced a valuable portable set that has 
since been adopted as a standard equipment 
by the Signal Corps. 

Meanwhile Professor Hazeltine was also 
conducting a radio and buzzer class to train 
operators for the Signal Corps. And then 
when Professor Ganz died, Professor Hazel- 
tine was appointed in his place to serve as 
head of the Department of Electrical En- 
gineering. 



454 



Radio Broadcast 




From Figures to Fame 



455 



THE SE 1420 

DURING the following year I was asked to 
join the technical staff of the radio 
laboratory at the Navy Yard at Washington," 
he narrates. " 1 spent the summer in Wash- 
ington doing miscellaneous development work 
and in the early fall 1 designed a radio re- 
ceiver which was standardized by the Navy 
Department and has been in wide use ever 
since. To Naval operators it is known as 
SE 1420. This receiver contained several 
novel features, and its design was of particular 
interest to me because it was based on the 
theoretical formulae which I myself had 
evolved and which were incorporated in my 
paper on 'Oscillating Audion Circuits. ' These 
methods were borne out so well by experiment 
that only a single shop model was constructed 
on which a few minor adjustments had to be 
made before the final drawings and specifi- 
cations were prepared for the submission of 
bids. 

"In the midst of my work I was stricken 
with an attack of influenza which kept me 
away from the laboratory for a few weeks. 
On my return I found that another member 
of the technical staff had practically com- 



pleted the development of a receiver similar 
to my own. The officer in charge of the work, 
Lieutenant W. A. Eaton, suggested that I 
abandon my development on the ground that 
time was pressing and that the other receiver 
was nearly ready. Had he given me definite 
instructions I would, of course, have obeyed 
him'. But inasmuch as he merely expressed 
a wish that I do so and because I had great 
confidence in my own design, I felt justified 
in continuing with my work. The result 
was that when these receivers were tested 
mine was shown to be distinctly superior to 
the other and it was eventually adopted. 
Although it is strictly against the copy-book 
traditions I feel that a subordinate is justified 
in going against the wishes of his superior if 
he is confident that he is right and if he is not 
disobeying positive instructions. 

ELIMINATING CAPACITY COUPLING 

IN THE design of this Navy "receiver I was 
particularly interested in trying to eli- 
minate capacity coupling between the pri- 
mary and the secondary circuits, for experi- 
ence had shown me that this was a source of 
much interference in reception. By suitable 
shielding I was able to eliminate all capacity 




THE STAFF OF THE ELECTRICAL ENGINEERING DEPARTMENT 

Of Stevens Institute of Technology. Professor Hazeltine, head of the Department, is seated in the first 

row, center. Front row, left to right, Professor F. C. Stockwell, Professor L. A. Hazeltine, W. P. Powers. 

Back row, H. L. Paulding, V. C. McNabb, Samuel Slingerland, and H. C. Roters 



456 



Radio Broadcast 



coupling in the primary and secondary cir- 
cuits except between two coils, one of which 
was necessarily in the field of the other. 
Then it occurred to me that I could minimize 
this coupling by partially shielding one of 
these coils through an auxiliary coil wound 
over it. I realized that this coil would pick 
up some current, and 1 quickly saw that this 
current might be employed to neutralize 
whatever capacity coupling remained. This 
was the first thought of capacity neutraliza- 
tion that I had, and I did not realize at the 
time that it was destined to be what one might 
call the keystone of the neutrodyne. The 
neutralization was actually incorporated in 
therNavy receiver although it was of the na- 
ture' of a refinement rather than of a necessity. 
"Later I attempted the design of an audio- 
frequency amplifier which would give a par- 
ticularly high amplification, but after a time 
I came to the conclusion that such an amplifier 
would oscillate persistently on account of 
the capacity coupling between the plate and 
the grid of the vacuum tube, in its circuit, for 
the plate and the grid circuits would be con- 
nected to similar transformers and would 
therefore be in resonance a condition par- 
ticularly conducive to oscillation. Almost at 
once I saw the solution the deleterious ca- 
pacity coupling. I suppose that my experi- 
ence with the Navy receiver helped me to 
reason out the method which I thus evolved. 
My experience seems to me to be an illustra- 
tion of the adage that the realization of a 
problem is frequently more important and 
more difficult than its solution. This neu- 
tralization of capacity coupling in vacuum 
tubes was the basis of the neutrodyne circuit, 
the practical development of which came 
several years later. 

THE WAY TO SOLVE PROBLEMS SOLVE THEM 

IN 1919 I started to devote my time to a 
study of the application of three-electrode 
vacuum tubes to the various problems of power 
conversion, with efficiency the primary ob- 
ject. This work was to some extent a con- 
tinuation of my earlier work on oscillating 
circuits, for the form of conversion which I 
first investigated was from direct current to 
high-frequency current as used [for radio 
transmission. The work was carried on much 
further, however, in order that it might 
include conversion of alternating current 
power into direct current power, of one fre- 
quency into another frequency, of direct 
current into alternating current of controllable 
frequency, and so forth. This new subject 



was a valuable background for my other 
work and made me realize that although two 
problems might not be closely related, they 
might, nevertheless, have a common ground 
in their respective solutions. 

"In my college work I constantly see many 
boys who seem quicker than 1 in absorbing 
mathematical theories, but they have not the 
fondness for work that leads to original inves- 
tigations. I have long believed that the 
prime requisite for success along mathematical 
lines and this applies to all scientific prog- 
ress is not so much a natural ability, as it 
is a certain fondness for the subject. The 
only way to learn to solve problems is to solve 
them. 

"I was engaged in the development of 
radio receivers during the fall of 1922 when 
my attention was directed to the immense 
possibilities of a receiver employing tuned 
radio frequency amplification. I knew that 
the great limitation of this type of receiver, 
which had thus far prevented its successful 
introduction, was in its strong tendency to 
oscillate because of the feed-back of the 
capacity coupling of the vacuum tube. This 
feed-back was accentuated by the tuned input 
and output circuits. I realized that my earlier 
work on the neutralization of this capacity 
coupling was directly applicable. A model re- 
ceiver was constructed to incorporate these 
ideas and it was christened the neutrodyne. 

" During this period, several manufacturers 
were eager to obtain a receiver of this sort, 
and Mr. I. P. Rodman, an officer of the 
present Garod Corporation who had become 
convinced of the great value of a tuned radio- 
frequency amplifier, had much to do with its 
development. The neutrodyne was first 
brought before the public at a meeting of the 
Radio Club of America in March, 1923. 

HOW INVENTIONS ARE MADE. 

THERE is much curiosity as to how in- 
ventions are made. In the earlier devel- 
opment of an art, most inventions are the re- 
sults of experimental discoveries, and this is 
often the case even in their subsequent 
growth. For example, Armstrong's inventions 
of regeneration and super-regeneration come 
under this category. My inventions, on the 
other hand, have all been the result of theor- 
etical studies, verified and modified by later 
experimental work. Again some inventions 
are the result of mathematical analysis as, 
for example, Pupin's and Campbell's loading 
coils on electrical filters in telephone lines. 
Although I have used mathematical analysis 



From Figures to Fame 



457 




PROFESSOR HAZELTINE AND A CLASS 

At work in a laboratory in the Department of Electrical 
Engineering at Stevens Institute at Hoboken, New Jersey 



quite freely in my studies, it so happens that 
my inventions have been based on elementary 
technical considerations and can be fully 
described either with or without the most 
elementary sort of mathematics. 

"Some inventions are made deliberately; 
that is, the inventor has a problem before 
him which he attacks in every way that he 
can think of until he solves it. It was in this 
manner that I made my invention of capacity 
coupling neutralization as applied to vacuum 
tubes and my high efficiency arrangements 
for power conversion with vacuum tubes. 

"It is interesting to compare the problems 
which confronted the engineers of a few years 
ago with those which puzzle them to-day. 
In the days immediately following Arm- 
strong's regenerative work, the great problem 
was to get vacuum tubes to oscillate, and I 
have spent many hours in trying to produce 
oscillations in circuits where the conditions 
were essentially unfavorable. In the Navy 



receivers which preceded mine, the idea of 
obtaining oscillations under all conditions of 
coupling and wavelength had been definitely 
abandoned and it required all of the refine- 
ment of calculation of which I was capable to 
produce controllable oscillation in my own 
receiver. 

"The problem of tuned radio frequency 
amplification, however, has been solved by 
the elimination of oscillations and I have spent 
as many hours getting rid of stray coupling 
and thereby stopping all tendency to oscillate 
as I have previously devoted to the encourage- 
ment of oscillation. So radio progresses." 

It may be that Professor Hazeltine has used 
the same method of progress for himself. In 
any event, he has come up by almost pure 
mathematical processes to vindicate the stu- 
dent. He has made inventions that others 
have repeatedly failed to approximate, and 
he has placed himself in the foreground of im- 
portant figures in the technical world to-day. 




RADIO BROADCAST Photograph 



FIG. I 



A parts picture. With the exception of the fixed condenser, all the parts entering in the construction 
of the detector amplifier are shown here. The numbers correspond with those of the parts list 



How to Build a Two-Stage 
Detector-Amplifier Unit 



BY JOHN B. BRENNAN 



BELIEVE that radio constructors are becoming more and more interested 
in building receivers thai will produce signals of excellent quality. As Mr. 
Brennan, technical editor of this magazine, brings out in this article, it is not now 
so important fust how much noise a receiver will deliver, or bow far it can be beard, 
but tbe quality of the program it produces. . This unit, which is designed to fit with 
the two-stage radio-frequency amplifier unit described by tbe same author in this 
magazine for May, 192$, has been especially designed to give the best possible 
quality. The cost of parts is not high, and the constructor will find that assem- 
bly and wiring is quite easy. THE EDITOR 




SLOWLY but surely the trend in radio 
is swinging toward quality. We are 
learning that it is not how much, but 
how good that counts in radio. 
There was a time when the radio store which 
had the largest horn sticking out its front 
window with a power amplifier behind it, 
assumed a kind of local radio supremacy due 
entirely to the pure force of the racket. 
Times have fortunately changed, and to-day 
we see many dignified if modest radio estab- 
lishments equipped with individual listening-in 
booths where receivers are on display and 
demonstration. 

So, too, the change has been felt in the design 
of radio apparatus. Parts and complete 
sets have been materially improved. Good 
voice and music quality and perfectness of 



loud speaker reproduction have assumed their 
rightful importance in design and construction. 
That old term "tremendous loud speaker 
volume" is slowly slipping into the discard. 
It is being helped along by an occasional 
shove in the form of an amplifier which 
produces loud speaker signals with clarity 
and fidelity. 
This paper describes such an amplifier. 

WHAT DO WE WANT IN AN AMPLIFIER? 

TO BE efficient, a detector and amplifier 
must have the qualifications of sensitivity, 
honesty of reproduction, ease of control, and 
must produce loud speaker volume sufficient 
for dancing. Its construction must be simple. 
The sensitivity largely depends upon the 
type of tuner employed to tune the incoming 



How to Build a Two-Stage Detector-Amplifier Unit 



459 



signal before it reaches the detector tube. 
However, the detector tube must also be 
possessed of qualities which will make of it a 
sensitive rectifier of these signals. 

Honesty of reproduction, or in other words, 
the property of the amplifier to repeat 
faithfully the sounds as transmitted, is a 
function governed by the selection of a 
suitable audio-frequency transformer, plus the 
intelligent use of A, B, and C batteries. 

All detector-amplifier circuits are pretty 
much alike. Their differences are mainly 
in the design which affects the control of the 
various parts entering into the construction of 
a completed unit. Undoubtedly a unit may be 
produced in which everything possible is varia- 
ble: C battery adjustment to the amplifiers, 
grid leak, grid condenser, tapped transformer 
primaries and secondaries, and B battery 
voltages. It is hardly necessary to state 
that the tubes would be individually controlled 
by separate rheostats. However, a unit such 
as this would soon loose its value if it were 
to be used in a permanent installation where 
there would be no need for all these controls 
once a satisfactory adjustment has been ob- 
tained. Such a completely variable unit 
would rather be suitable for the laboratory. 

The volume produced by an audio amplifier 



depends upon the number of stages of ampli- 
fication which may safely be used without 
overloading the amplifier tubes. Volume 
also depends upon the sensitivity of the de- 
tector and the ability of the amplifier to take 
whatever is produced in the detector and 
amplify it without altering the signal charac- 
teristics. Briefly explained, this means that 
some amplifying transformers have the ten- 
dency to favor some voice and music notes 
over others, depending upon the electrical 
and mechanical makeup of the transformer. 
The distributed capacity in transformer wind- 
ings causes a favoring of the lower fre- 
quencies over the higher frequencies. Also, 
when little iron is used in the core construc- 
tion, it becomes over-saturated by the forceful 
variations of electromagnetic flux and prevents 
the transformer from functioning successfully. 

GOOD QUALITY AND SUFFICIENT VOLUME 

THE detector and two-stage audio- 
frequency amplifier described here is the 
result of experimentation along the lines as 
explained above. It has been reduced to a 
practicable working unit producing a very 
high quality of signal with plenty of volume. 

This detector-amplifier may be used with 
any tuner now available, but has been especi- 



DETECTOR 



FIRST STAGE 
A.F. AUDIO 

TRANSFORMER AMPLIFIER 



A.F. 

TRANSFORMER 



SECOND STAGE 

AUDIO 
AMPLIFIER 




- O A O -O 



FIG. 2 

The circuit of the detector-amplifier. The numbered units refer to those panel controls as marked on the 
panel illustration Fig. 3. In wiring it is well to make frequent use of this circuit and the schematic wiring 

diagram, Fig. 7 



460 



Radio Broadcast 



I 

. 

r 




5" 




i 
5" - 


Screw Holes 
All Na27 

L 




Working .^ 
Center Line 

PANEL 3 /i 

a" ^_ 




uV -i 


4 


) * 
%Hole 

6 n x7"xlO" t 

1 
C 


1 




fh 

%" Hole! 





^" Hole. 


) - t 


: /^h 




vjy 


1 

fk / 

^l ' ' " " 


>--J- 

"i -^ 

r-l V. 


1 "^ 

I ! c 

T^ 

L^ 


1 

J ! i 
^^" Hole 


7~ 
%" Hole 


cp * 

c y 




1QH 5^ 



4 



FIGS. 3 AND 4 

This front view of the panel indicates the symmetrical layout which has not caused any sacrificing in effi- 
ciency for the sake of appearance. Ample room on the upper side allows for the mounting of a filament 
voltmeter and plate milliammeter or plate voltmeter. The working drawing above shows the panel layout 




RADIO BROADCAST Photograph 



How to Build a Two-Stage Detector-Amplifier Unit 



6V 




SUPPORT BRACKETS 
(Material: V B 



FIG. 6 
The angle bracket details. Two are required 

ally designed as the audio unit for the two 
stage radio-frequency amplifier described in 
the May, 1925, RADIO BROADCAST. 

The circuit comprises a vacuum tube de- 
tector with variable grid leak and independent 
filament rheostat and a two-stage audio 
amplifier with filament controlled by one 
rheostat. Large core audio-frequency trans- 
formers of a ratio of approximately 3 to i, 
and a C battery bias upon the grids of the 
amplifying tubes are important items entering 
into the construction. None of the adjust- 
ments is exceedingly critical but are found 
to be of actual necessity when maximum 
service is desired. 

All thebindingposts for theconnection of the 
tuner, batteries and loud speaker are mounted 
upon the rear of a bakelite shelf which also 
supports the audio transformers. 

A filament switch, the grid leak and con- 
denser, rheostats, sockets and jacks are 
mounted upon the panel. The bakelite 
sub-base is mounted upon the brass angle 
brackets which are fastened to the back of the 
panel. 



WHAT PARTS TO. USE IN THIS UNIT 

CATISFACTORY results with this design 
*-} depend entirely upon the selection of 
many of the same parts as employed in our 
construction. This is quite logical. It is 
probable that another type of amplifier can 
be designed using other parts but that's 
another story. 

The parts employed in the construction of 
this unit are listed as follows: 

1. 3 Federal sockets panel mounting 

2. 2 Bradleystats 

3. i Bradleyleak, with .00025 mfd. condenser 

4. 2 Carter Jacks, i open single-circuit, I 

closed single-circuit 

5. 2 Rauland Lyric audio-frequency transform- 

ers ratio 3.95 to i 

6. i Carter filament switch 

7. i Panel 7 x 10 x T \ inches 

8. i Panel 3^ x 9 T 3 5 x T 8 ff inches 

9. 10 Eby binding posts 

10. Brass strip 20 x \ x \ inches 

11. Bus wire lugs 

12. 14 \ inch x g e j Round head machine screws 

with hex nuts. 

13. 6 \ inch x -fa Flat head machine screws 

with hex nuts 

14. i - .0005 mfd. fixed condenser 

The reader will probably ask, "can other 
transformers be used instead of those shown?" 
Of course, yes, but so can other parts be used 
-throughout the construction. If this variation 
is allowed in parts selected, the individual 
constructor would have to lay out his own job. 
He would, of necessity, have to rearrange the 



-. 4%'- ; 



r *'-f 



jt 



L t--'-- 



All Holes Na 27 Drill 
O 



<j> (j) <j> 






SUB PANEL 



t 



Q 3/ '' 

9^6 - 



FIG. 5 

In the layout of the sub-base, the dimensions are marked starting from the center line. By 
actually placing the audio transformers in place, their mounting holes may be scribed 



462 



Radio Broadcast 
SUB BASE 




FIG. 7 

Is a schematic wiring diagram of the completed receiver. For the sake of 
clearness, the panel is represented as being on the same plane as the sub-base 



various mounting holes on the panel and also scheme of construction and that is hardly new. 

the sub-panel holes would be changed. Therefore for those who wish to benefit by the 

If the parts were not thoughtfully selected experience gained in the test of several types 

there would be nothing left but the idea and of apparatus, it is suggested that they con- 



How to Build a Two-Stage Detector-Amplifier Unit 



463 



form to the selection of parts as closely as 
possible to the list as shown. 

The heart of the unit is the two audio- 
frequency transformers. They have been 
selected because of the large cores upon which 
are wound plenty of wire. These two features 



RADIO BROADCAST Photograph 

In laying out the panel, place it face down 
on a table with its length running right and 
left. Now divide the length into two sections 
evenly, both of five inches each. The dividing 
line is the working center line. Working up, 
three quarters of an inch from the bottom 



TWO STAGE 
RADIO FREQUENCY AMPLIFIER 



DETECTOR 
TWO STAGE AMPLIFIER 




-A- B+90 



FIG. 8 



How the detector two-stage amplifier would be connected to the two-stage radio-frequency amplifier 
described in the May, 1925, RADIO BROADCAST. The cut above shows the two units connected 



alone prevent over-saturation and insure 
against overloading. 

Those used in this amplifier are of a low 
ratio and are capable of taking a very strong 
signal and amplifying it without changing its 
characteristics. The circuit employed is that 
of Fig. 2. 

The numbered symbols in Fig. 2 are those 
with variable controls that are mounted on 
the panel. They may be identified in the 
panel illustration Fig. 3. 

ASSEMBLY IS EASY USING THE NUMBERS 

THE construction of the detector-amplifier 
is almost entirely a matter of assembly, 
and wiring. We suggest proceeding as 
follows: After the parts have been obtained, 
the panels are prepared by drilling all the holes 
and graining the surface by rubbing with 
fine emery paper. 



scribe a line (i) across the length of the panel. 
On it will be located the two jacks. Then 
one half inch above it scribe another line 
(2) all the way across. This is for the socket 
mounting holes. Another line (3) is scribed 



SUB BASE 

Output B ^A ^C Input 

Q Q Q O O ' 




To Tuner 



FIG. 9 

Here is how the batteries, A, B, and C are con- 
nected to the binding posts on the sub-base 



464 



Radio Broadcast 



Plate Variometer 
Inserted in Plate 
Circuit of 
Detector Tube 






7 


4 

0005 H 
mfd 





-6 A + 



B-t-90 



if inches above the last one for the grid 
leak and two rheostats. The filament switch 
hole intersection line (4) is marked directly 
on the center line 2 inches above the 
line No. 3. 

Working out from the center line on line No. 
i, the two jack holes are located \\ inches 
away. The mounting holes for the brass 
brackets are located on this line f of an inch 
from the sides of the panel. 

Now jump up to line No. 3 for the rheostats 
and grid leak, etc. One is centrally located 
on the center line and the other is 3 inches 
to the side as is the grid leak hole. After 
locating these three points, continue the scriber 
lines down so as to interesect line No. 2. Then 
coming back to line No. 2 the socket mount- 
ing holes are located f of an inch either 
side of the point of intersection of the rheostat 
hole lines. The complete layout is shown 
in Fig. 4. 



Attaches To 

Plate of Detector 

Tube 



Several tuner and radio-frequency amplifier 
circuits which may be used; with this de- 
tector amplifier, i. is a standard tuner 
with primary and secondary, the latter 
shunted by a .0005 mfd. condenser; 2. is 
the old standby, the varipmeter-vario- 
coupler tuner; 3. is the variometer antenna 
tuner; 4. a non-radiating radio-frequency amplifier 
and tuner; 5. the Reinartz tuner; and 6. a loop 
and r. f. circuit. In the detector circuit, the return 
of the grid circuit is made to the negative side of 
the A battery line. If results are not satisfactory, 
try making this connection on the positive side 
of the A supply 



This completes the panel. The sub-base 
dimensions may be laid off in a similar manner 
and are shown in Fig. 5. 

The binding posts are situated three quar- 
ters of an inch from each other beginning at 
the center line. The holes for screws holding 
the sub-base to the brass brackets are located 
on each end j of an inch in from the edge. 
The transformer holes are given but are not 
accurate for all transformers of the same man- 
ufacture. Therefore, in laying out these 
holes it is well to place the transformers on 
the base so that the holes on one side are -^ 
of an inch from the front edge. Then holding 



How to Build a Two-Stage Detector-Amplifier Unit 



465 




FIG. I I AND FIG. 12 

The top side with all parts excepting the bypass condenser in view. Note 
how the two audio transformers are mounted with their cores at right angles 
to each other. Much of the wiring is on the under side of the sub-base 



4 66 



Radio Broadcast 



the transformer in place, mark the holes with 
a scriber. 

The brass brackets are bent and drilled 
in accordance with the layout shown in 
Fig. 6. 

With this preliminary preparation ac- 
counted for, the work of assembly is next in 
line. The several parts are mounted in order 
named, from the top of the panel down; first 
filament switch, then rheostats, and grid 
leak, next sockets and finally jacks. 

For the sub-base, first mount all the binding 
posts having the lugs on the under side of'the 
panel and pointing in toward its middle. 
Next mount the panel upon the brackets and 
after this is done, secure the two transformers 
firmly with |-inch x -j% round head machine 
screws. The cores are placed at right angles 
to each other as may be seen from the sche- 
matic wiring diagram Fig. 7 and the illustra- 
tions. 

The completed sub-base unit is fastened 
to the panel by two round head brass or nickel 
plated machine screws ^ inch long. 



THE UNIT 

IN AN assembly job as compact as this, it 
is absolutely essential that insulated wire 
be used, at least where there is danger of short 
circuits. In the unit described, insulated 
wire has been used throughout. Contrary 
to what one might think, the wiring job is 
simplicity itself. It is only to be remembered 
that the wires should run direct from one part 
to the other without unduly twisting or bend- 
ing them. The schematic wiring diagram in 
Fig. 7 will be of aid here. 

Wherever possible, lugs have been clamped 
down under terminal nuts to provide an 
easily accessible point of soldering. 

As a standard detector-tv/o-stage audio 
amplifier, this unit is admirable for use around 
the laboratory where the experimenter is fre- 
quently trying new tuner circuits and requires 
a means for detecting and amplifying his re- 
ceived signal. Its primary purpose is for use 
with the two-stage radio-frequency amplifier 
described in the May, 1925, RADIO BROADCAST. 




FIG. 13 
Looking at the amplifier from the right side 



How to Build a Two-Stage Detector- Amplifier Unit 




FIG. 14 

The left side view 



The circuit diagram, Fig. 8, shows how these 
two units may be connected together. 

Plate voltages of from 90 to 120 may be 
used on the two audio stages while for the 
detector 45 to 90 volts will be suitable. ' No 
definite voltage requirements are specified 
as this depends entirely upon the tubes and 
transformers used. Six-volt tubes will prob- 
ably give greater satisfaction in this unit, 
although it is of course entirely possible to 
use one and one half and three- volt tubes. 

The loud speaker may either be plugged 
into the last jack or the cord tips fastened in 
the output binding posts. The jack for the 
first stage is not of the conventional double- 
circuit type but is a single closed-circuit jack 
which includes the phones or loud speaker in 
series with the primary of the first transformer 
when the plug is inserted. 

OPERATION OF THE AMPLIFIER 



the unit has been adjusted for 
one particular time, for instance, an 
evening enjoyment of a radio program, there 



is nothing that need be touched with the 
possible exception of the grid leak. Tubes 
should be burned only as brightly as is con- 
sistent with clear and sufficient volume. 
To go beyond this point usually results in 
decidedly decreasing the life of the tube. 

The batteries are connected to the binding 
posts of the amplifier as shown in Fig. 9. 
The C battery voltage will vary conversely 
with the B battery voltage applied and may 
conform with this table: 

C Volts 
3.0 to 4.5 
4. 5 to 6.0 
6.0 to 9.0 
9.0 to 12.0 

The tuner unit output is connected to the 
detector-amplifier input at its input binding 
posts. Amplifier output posts are provided 
which allows the use of a loud speaker without 
plugging into the jack. Several tuner and 
radio frequency circuits with which this unit 
might be used are shown in Fig. 10. 




4 68 



Radio Broadcast 




RADIO BROADCAST Photograph 
FIG. 15 

Simplicity in wiring is clearly indicated in this bottom view. It also shows the need for accuracy 
in layout, as there is not much room to spare for the sockets between the two brass brackets 



If there is the slightest trace of a high- 
pitched singing noise, it is well to ground the 
negative side of the A battery and the cores 
of both audio-frequency transformers. 

Where trouble is apt to be encountered, it is 
suggested that the constructor proceed first 
by re-checking the entire circuit diagram with 
the wired circuit of the unit. Sometimes it is 
possible that transformer windings are open- 
circuited or bypass condensers short-circuited. 
Be sure also that positive contact is made 
between the several blades of the jacks and 
that the filament switch is working correctly. 
Tube prongs may also be bent down too far, 



preventing the tube from making contact 
with the socket blades. 

From the several assembly and wiring 
photographs it will be seen that some leads 
have been passed through holes drilled for the 
purpose in the sub-base. Many of the leads 
running from the sub-base assembly to the 
panel pass through the narrow space between 
the sub-base and the rear of the sockets. 

When enclosed in a suitable cabinet, this 
detector-amplifier in appearance will grace 
any installation and is admirably adapted 
for the special requirements of the experi- 
menter. 



The material appearing in this magazine is fully protected by copyright, and 
editors of periodicals are advised that unauthorized publication of circuit 
diagrams, technical descriptions, and parts or the whole of articles, without due 
permission and credit, is an infraction of the law. Those who wish to reprint 
material appearing in these pages are asked to communicate with the editor. 



" Point of^ 

by Koines leg 



Summer Radio Programs Are Attractive 



WE IMAGINE that the broad- 
cast program directors, har- 
assed fellows that they are, 
breathe a sigh of relief when the 
summer season comes around. A glance at 
the daily radio programs in the newspapers, 
bought these steamy summer days, shows that 
there is plenty of interesting entertainment 
which can be led into the willing maw of the 
domestic loud 
speaker. At the 
risk of incurring 
the wrath of 
those who make 
what is flip- 
pantly called a 
livelihood from 
the business of 
transportation, 
we should like to 
suggest that the 
faithful radio set 
can provide en- 
tertainment and 
amusement in 
the coolness of 
one's home which 
make a trip to 
the scene of the 
festivities entire- 
ly unnecessary. 

Although the 
concert season 
has closed, and 
the members of 
orchestras which 
have been heard 
from many sta- 
tions during the 
winter and spring 
with so much 




FRITZ REINER 

The famous conductor of the Cincinnati Symphony Orchestra 
which has been heard over station WLW, of Cincinnati. Mr. 
Reiner, who is quoted elsewhere in this department, thinks 
that radio can do much to elevate American musical taste. 
His own activities through WLW have done a great deal toward 
giving broadcast listeners music of unequalled quality 



pleasure have scattered, there are still many ex- 
cellent bands which will be on the air from vari- 
ous stations during the summer. The United 
States Marine Band is probably the best known 
of musical organizations of this sort that can 
be heard during warm weather. Every Wed- 
nesday evening from five to six thirty, East- 
ern Standard Time, this band can be heard 
through stations WRC of Washington and wjz 

of New York. 
These late after- 
noon concerts 
will supplement 
the regular 
weekly concerts 
played in the 
Sylvan Theatre 
at Washington 
which are broad- 
cast every Thurs- 
day night from' 
seven thirty to 
nine, Eastern 
standard time. 
WEAF and eight 
others are broad- 
casting several 
concerts weekly 
of the Goldman 
band from the 
bandstand on the 
campus of New 
York University, 
beginning 318:30 
and concluding 
at 10:15 Eastern 
daylight saving 
time on the eve- 
nings concerned, 
wjz, WGY, and 
WRC will broad- 



470 



Radio Broadcast 



cast three times weekly concerts of the New 
York Philharmonic Society. The orchestra 
plays in the Lewisohn Stadium, New York. 

Listeners to wwj, of Detroit, remember 
with much pleasure the concerts of Schme- 
man's Band which have been broadcast from 
Belle Isle park in that city. Alert program 
managers in many other cities promise bands 
of high grade. 

And sporting events seem to get on the air 
more regularly during the warmer months, 
which is probably most simply explained by 
the fact that there is more activity of this sort 
at this time of year. The famous Indianapolis 
automobile races were broadcast from WGN 
at Chicago on Memorial Day with great suc- 
cess. College baseball games were on the air 
in many sections of the country in the weeks 
before academic doors closed for the summer 
holiday, wjz handled particularly well the 
job of reporting a recent game between Yale 




GOVERNOR NELLIE TAYLOE ROSS 

Of Wyoming and Governor Clarence J. Morley of Colorado, before the micro- 
phone of KOA, at Denver. Governor Ross shares national honors with 
Governor " Ma" Ferguson, of Texas as the first members of their sex to guide 
the political destinies of an American state 



and Princeton to say nothing of the Yale 
Commencement exercises in June. 

Station WJAZ, of Chicago, is making plans to 
broadcast the classic Lake Michigan sailing 
yacht races between Chicago and Mackinac 
Island. A small short wave transmitter will 
be set up on a power boat which will follow 
the yachts as they speed up the lake. 

It is unfortunate that one or more of the 
enterprising Eastern broadcasters do not 
arrange to broadcast more of the college crew 
races, wjz made a brave stab at it not long 
ago when they put a short wave transmitter 
aboard the yacht Elco in the Harlem with 
the capable Major J. Andrew White at the 
microphone and broadcast the Childs' Cup 
race between the eights of Columbia, Penn- 
sylvania, and Syracuse. The Poughkeepsie 
races in June afforded a tremendously exciting 
event to listeners interested in sports. Major 
White at the traveling wjz microphone 
brought his listeners 
along with him by the 
color and imagination 
of his picturesque de- 
scriptions. 

In the main, out-of- 
door broadcasting is 
more successful than 
might be thought. 
Reverberations present 
in a large hall make 
the problem of properly 
broadcasting an or- 
chestra or band most 
difficult. As Mr. Carl 
Dreher suggests this 
month in "As the 
Broadcaster Sees It" 
open air broadcasting 
is usually quiet and free 
from the unpleasant 
effects of sound, bounc- 
ing about where it 
should not go. And, 
barring the barking of 
disturbed and inquisi- 
tive dogs, and the squal- 
ling of tired children, 
the broadcaster who 
sets up microphone and 
speech amplifier in the 
open air is usually quite 
successful. 

However, a few weeks 
ago, wjz was broad- 
casting the ceremonies 
incident to the unveil- 



Open-Air Broadcasting 



471 




MARION DAVIES 
Who was heard at a "Motion Picture and Vaudeville Star's Radio Party" from station WIP, in Philadelphia 



ing of a tablet to Thomas A. Edison, from 
Menlo Park, New Jersey. The speeches were 
in the open air and came through in excellent 
fashion. But the scene of the affair was close 
to the main line of a railroad, and at times 
during the broadcasting, the hasty puff of the 
engines came through the microphone with 
such force as to interrupt the words of the 
speakers. Governor Silzer, of New Jersey, 
who made one of the principal addresses, 



remarked that the occasion was probably the 
first time that the State of New Jersey was in 
direct competition with the railroads. 

Many of us have felt, during the broad- 
casting of a prize fight, to choose a happy 
example, that the miscellaneous noises the 
cheering of the crowd, the gongs and bellow 
of the announcer in the ring are a decidedly 
necessary and desirable part of the affair. 
The commercial noises of a railroad, however, 



472 



Radio Broadcast 




THE SANDMAN OF STATION KHJ 

At Los Angeles. Those who have that unusual ability to talk to 

children instead of down to them are heard from many broadcasting 

stations, and the "Sandman" of KHJ is one of the most able and 

most popular of the broadcasters of this sort 



After that, it seemed as if news- 
paper and magazine radio critics 
increased even as the beasts of 
the field. 

There are now probably 
anywhere from three to five 
million radio receivers in this 
country, if one accept the most 
credible estimates of those 
arithmetical persons who inter- 
minably compile statistics on 
the number of radio listeners. 
That chip falling where it may, 
however, it is our hope that 
some of the owners of the five 
million receivers may find some- 
thing interesting in these pages 
each month. That object being 
attained, as J. Caesar would say, 
we hope to read your letters of 
opinion and comment on broad- 
casting our mutual concern. 

What Makes a Broadcast- 
ing Station Popular 



are not much of an addition to most outdoor 
pick-ups. 

A Statement of Policy 

IT IS no easy task to take up "The Listener's 
Point of View" where Miss Mix left it. 
In the fourteen months that she wrote this 
department, she succeeded in building up a 
following of readers in all parts of the country 
which any writer might envy. This was 
natural indeed, for her comments and criticism 
combined in delightful fashion, great breadth 
of knowledge of matters musical and a charm- 
ing style of presentation. 

The present writer, readers willing, will 
attempt to carry on. His design involves news 
and comment of broadcasting stations, artists, 
and broadcast programs, and all else which is 
of the ether etherial. 

It was in February, 1924, that the editors 
of RADIO BROADCAST planned this department, 
and in the April, 1924, magazine that Miss 
Mix's first department appeared. A few days 
before the April number appeared on the news 
stands, the New York Herald Tribune began 
their daily broadcastingcritique" Last Night on 
the Radio" written by the caustic Mr. Raymond 
Francis Yates, who used the name "Pioneer." 



IN THE first exciting days of 
broadcasting, the very act 
of receiving the sounds of 
tinny phonograph records and the noisome 
regularities of a mechanical piano was re- 
garded by the wondering public as a stunt, 
a kind of theatrical laboratory experiment. 
And many of our broadcast directors have 
never allowed that feeling to weaken in the 
minds of what they are pleased to call their 
clientele. While listeners are able to depend 
on this station and that for regular features of 
one sort or another, they look to others to 
supply them with something new, curious, 
outre. 

Witness the Philadelphia broadcaster who 
sent a studio favorite in a diving suit to the 
bottom of the ocean near Atlantic City, where 
for some fifteen minutes he regaled his listeners 
with sub-aqueous, non-scientific platitudes. 
A year ago, much journalistic to-do was ex- 
cited over the broadcasting of the sounds of 
the circus. And so we have had various at- 
tempts at broadcasting from an airplane, none 
of them especially successful. 

The learned Secretary Wilbur arranged with 
his Naval radio and publicity experts to 
install a low powered broadcasting set on the 
Los Angeles when she made a recent all-day 
voyage over Philadelphia, laden with a cargo 
of merchants. Gar Wood's "race" "between 
one of his speed boats and the Twentieth 



Are Broadcasting "Stunts" Desirable? 



473 



Century Limited was reported by radio from 
an airplane flying over the racers on their two 
hour trip down the Hudson from Albany to 
New York. One hesitates to conjecture what 
the next stunt will be. In some respects our 
English friends are not far behind; was not 
the song of the nightingale broadcast from 
2LO to the tune of newspaper space, measur- 
able only in feet? 

The directors of broadcasting stations will 
admit, almost to a man, that they are, after 
four years, still experimenting. They are not 
yet reaHy certain what the public wants. But 
we are certain that the public is primarily 
interested in the best. If a broadcasting 
station has gained a reputation for excellent 
classical music or for jazz music of good 
quality, or for good lectures and speeches, or 
whatnot, that station can be best kept in the 




favor of the public by a continuance of the 
policy. We doubt very much that temporary 
bursts of publicity, gained from the studio 
presence of movie stars who tell radio listeners 
of their innermost thoughts, or by the broad- 
casting of a jazz melange from a steamship 
at dock can do much permanently to gain 
public favor. The station which daily meets 
the real wishes of its listeners is the one whose 
popularity will last. 

An Orchestra Conductor Speaks 
About Radio 

THE greatest hope for radio -is that it 
may bring good music to all parts of 
this vast country, and awaken in the 

soul of America a thirst for the best in music. 

Radio should teach the people to learn to love 
good music. There can 
be no cultural progress 
so long as people are 
given only what they 
already enjoy. Let us 
teach the people to 
want something which 
has not yet been given 
them. 

"For the most part, 
radio is considered by 
everyone as merely a 
medium of entertain- 
ment. And this en- 
tertainment is almost 
entirely music. This is 
a desecration. Music 





MAY SINGHI BREEN AND PETER DE ROSE 

Who have been heard from station WEAF and others in banjo and piano duets. Miss Breen is a banjo player 
of striking talent and is well known to radio audiences. The insert shows the head of a banjo she has 
used in many radio studios with its signatures of radio favorites, including Jack Yellen, Doctor "Billy" 

Axt, and George Gershwin 



474 



Radio Broadcast 



should be a divine service to humanity. It 
is a pleasant thing when enjoyed as a mere 
pastime. But with every mental uplift, there 
must be a consequent struggle, and in order 
to comprehend the divine beauty of music, 
one must be willing to make the sacrifice of 
laboring to understand. 

"One of the beautiful possibilities of radio, 
as I see it," continues Mr. Fritz Reiner, 
conductor of the Cincinnati Symphony 
Orchestra, "is to teach the fundamentals of 
music to the people. Americans have plenty 
of sentiment; they are not cold blooded. 
Their only drawback is that they do not know 
how to express themselves. Teach them the 
fundamentals of music and the genuis of the 
nation will assert itself. When the whole 
nation loves good music it will pay for good 
music and thus afford an incentive to its youth 
of talent and intelligence." 

Mr. Fred Smith, director of station WLW 
gathered these interesting ideas from Mr. 
Reiner, who is accepted as one of the outstand- 
ing symphony conductors now in America. 
WLW has done much in furnishing good music 
to its listeners. When the new long range 
station of WLW was opened, Mr. Reiner had 
charge of the dedication program, when he 
conducted a special concert with an orchestra 
of fifty picked men from the Cincinnati Or- 
chestra, At other times, his Orchestra has 
been heard from WLW. 

Other stations are known for the good music 
on their programs. Station KSD of St. Louis 
has the record of broadcasting every sym- 
phony concert of the St. Louis Symphony 
during the past season. The Detroit News 
orchestra, a permanent part of the studio staff 
of station wwj, is composed of members of the 
talented Detroit Symphony Orchestra. Sta- 
tion WEAF, of New York has broadcast regu- 
larly the concerts of the New York Philhar- 
monic Orchestra. The good music that Mr. 
Reiner hopes American listeners can hear is 
being sent out from various parts of the 
country, though it has to force its way through 
a blanket of jazz. It is the contention of many 
that enough good radio music is being played 
now so that the taste of American listeners is 
slowly being raised. More will be said of 
this later, however. 

Broadcasting, Canadian Style 

IT IS bad enough," someone remarked, with 
what was probably a vocal twinkle, 
"when one listens to a Floridan or a 
Californian sing the praises of his climate to a 



small group, but when they buy radio stations 
and, in a manner of speaking, tell the world 
about it, the situation becomes serious." 
Good residents of Florida and good residents 
of California have bought broadcasting stations, 
but it must be recorded that they are reason- 
ably restrained about the climatic merits of 
their communities. 

But now are the Canadians fallen from 
virtue. CKAC, the excellent station of La 
Presse at Montreal, cannot withold the 
attractions of the Province from a listening 
world. On their program for the two weeks 
beginning May 3Oth, appeared the following 
legends. 

June 2: 8:30 P. M. Talk on Attractions of Province 
of Quebec 

June 6: 8:30 P. M. Road reports; talk on the at- 
tractions of the Province of Quebec 

June 9: 8:30 P. M. Talks on the attractions of the 
Province of Quebec. Road conditions reports 

June 13: 8:30 P. M. Studio program; talk on 
Quebec attraction. 

Sir Robert Falconer, President of the Uni- 
versity of Toronto, has been giving a series of 
lectures before English Universities on the 
general subject of Canadian and American 
relations. One of the interesting points that 
he made was that Canada and the United 
States were closer in some respects than 
England and Canada. This is due, Sir Robert 
thinks, to the fact that Canadians read 
American magazines and hear American 
broadcast programs, both prepared for purely 
American consumption. A Rotary Club speech 
from some Middle West city is heard by a 
group of far-off ranchers in distant Canada. 
So, thinks Sir Robert, do American ideas 
penetrate Canada. 

But now the American leaven is working, 
and listeners on this side of the border are 
getting some of their own medicine. A new 
and amusing form of reciprocity! 

General Dawes as a Musician 

SINCE Charles G. Dawes, Chicago 
banker, attained world wide, and 
later national fame through his feats 
of statesmanship and politics, broadcast 
directors have discovered that this picturesque 
and extraordinary person is a composer of 
parts. Several of his compositions including 
his "Melody in A Major" have been heard 
by radio listeners. Which calls to mind the 
Washington experience of Mr. Heywood 
Broun, the genial columnist of the New 
York World who inquired of a politically in- 



The Demand for Old Fashioned Music 



475 



clined woman of his acquaintance how the 
General ranked among composers. 

"Does he write good music?" asked Mr. 
Broun. 

"That all depends," the lady answered, 
"on whether you are for or against changing 
the rules of the Senate." 

When Central Americans Overhear 
the United States 

A/1ER1CAN broadcasting stations are 
picked up 
throughout all 
the Central American 
republics, and pro- 
grams are enjoyed as 
a rule, though there 
has been some com- 
plaint regarding the 
quality of music," re- 
ports R. A. Lund- 
quist, chief of the 
electrical equipment 
division of the Bureau 
of Foreign and Do- 
mestic Commerce at 
Washington, after a 
recent trip through 
that territory. 

"O n the other 
hand, in several cases, 
radio fans who had 
instruments of suffi- 
cient selectivity and 
range to choose be- 
tween American sta- 
tions, commented 
favorably on this 
point, saying that 
they were surprised 
to note the quality 
of music received 
from small towns 
where the programs 
were given by local 

talent. This was especially true of the 
Middle Western states which are apparently 
in some sections picked up more readily than 
are those in the East or far West." 

Those who use care in tuning and pick up 
some of the smaller mid-West stations will 
hear good music, well played. In these locali- 
ties, there are numberless amateurs of the voice, 
piano, and violin, whose names never appear on 
great concert programs, who are heard over the 
radio from stations the length and breadth of 
the country. 




TEN EYCK CLAY 

The new director of the WGY Players. Station WGY 

was the pioneer in securing and presenting radio 

plays and has found that radio listeners favor short 

plays, prepared especially for broadcasting 



"We have used the home type of music and 
program at our station," said Mr. Henry 
Field, of Shenandoah Iowa, owner of station 
KFNF, "partly because it was the easiest thing 
for us to do, and partly because I had the 
definite opinion that people were hungry for 
the home type of music. We feel that there is 
a big demand, which many people do not sus- 
pect, for simple, wholesome, old-fashioned 
music. I find that a surprisingly large num- 
ber of listeners of all classes are very tired of 
cabaret music and would like to have more^of 
the old home-town 
stuff." Mr. Field was 
addressing one of the 
committees at Secre- 
tary Hoover's annual 
radio conference at 
Washington, last Oc- 
tober. He continued, 
"I have a letter in 
my pocket from a 
prominent man here 
in Washington who 
listens-in regularly. 
Both he and his wife 
are small town peo- 
ple. It would be in- 
teresting to hear their 
comments on the 
cabaret type of music 
which they get from 
so many stations, and 
how "it seemed like 
a breath of air from 
the prairies" to hear 
Gospel hymns over 
the radio." 

Fewer jazz orches- 
tras and a bit more 
of what may be 
called standard music 
from broadcast sta- 
tions would meet 
with great favor 
from the public, if 
signs may be taken as any crite- 



existmg 
rion. 



Broadcast Miscellany 



o 



NE of the two women governors in the 
United States was heard over the 
radio from station KOA, Denver, some 
weeks ago. She spoke on "Cheyenne Frontier 
Days and Wyoming of To-day." Listeners 
were much interested in her description of the 
change. in her native state. 



Radio Broadcast 



SIGNING off," that phrase heard from 
every broadcaster at least once during 
the day's program, is to be abolished at 
station WLW. Some "appropriate quotation" 
will be given instead, and finality achieved by 
"Good night." The news bureau of WLW 
offers as a sample quotation: "Great thoughts, 
like little deeds need no trumpet; good night." 
"Signing off" is a hold-over phrase from the 
telegraph side of radio, and, like the use of call 
letters to designate stations, has little to do 
with broadcasting. We think this is a step 
in the right direction, but why complicate the 
closing with a sententious quotation? Isn't 
a simple "Good night" enough? 

LISTENERS are constantly on the search 
for an up-to-date list of broadcasting 
stations, their wavelengths, power, and call 
signals. One of the best of the many books 



we have seen is Dunlap's Radio Call Book. 
In addition to listing all the radio broadcasting 
stations of the world, the book contains their 
slogans, and is kept up to date by a monthly 
supplement containing changes and cor- 
rections. It may be secured for $i from Dun- 
lap's Radio Call Book Service, Box 88, 
Flushing, New York. 

CORRESPONDENCE from controversial- 
^> minded readers of this department is 
invited. We are anxious to present the 
opinions of readers on broadcasting and its 
problems, and it is our hope that this depart- 
ment will be considered a forum, open to any 
one who has something to say and says it with 
clarity and intelligence. Correspondents are 
asked to do us the courtesy of signing their full 
name and address, which will not be used if 
if they so request. 




THE MECHANICS OF A RADIO PLAY 

In operation at WGY, when the WGY Players put on "Rip Van Winkle." Ten Eyck Clay, director and lead- 
ing man of the Players is at the microphone as Rip. Frank Oliver [is 'pouring water through a sieve to give 
the effect of rain. In the background are the thunder sheet and the wind machine. The radio Players seem 
to be enjoying their share of the performance as much as the listeners, which is putting it mildly 



The Revolution in the Art of 

Teaching 

The Long Arm of Radio Is Bringing the Best from the College to the Re- 
motest Districts What the Public Wants and How Their Wants Are Being Met 



BY FREDERICK P. MAYER 



THE long trips on cold trains in win- 
ter, the meals in poor restaurants, the 
leaving of work and papers to do what 
seemed of doubtful permanency are 
things that only the professor who used to 
give lectures to small groups in various com- 
munities can understand. 

The university extension course was given 
in the high school auditorium of some small 
town where there were enough high school 
and grade school teachers and enough inter- 
ested club women to make an audience of 
perhaps a hundred. To this small group, the 
university sent out, at 
a heavy financial out- 
lay, a part-time 
"extra-mural" teach- 
er who traveled to the 
small town from his 
school, delivered his 
lecture to the one 
hundred teachers, and 
went home again 
with little done for 
the outer world of 
popular education 
and little done for 
himself and his school. 
But radio is chang- 
ing all this. The pro- 
fessor of to-day pre- 
pares his lecture for 
his radio class with 
greater care than he 
gives to the class lec- 
ture on the campus. 
His audience may in- 
clude professors in his 
own field who are 
eager to check the 
work his school is do- 
ing; he knows that 
business men and high 
school boys, men in 
barber shops and 
clubs are his class. 



Giving the Teacher the Air 

IS ANOTHER experiment with the possi- 
* bilities of radio. Mr. Mayer does not 
attempt to tell what every university and 
college in the country has tried to do with 
broadcasting, but he does tell what has been 
in progress at Pittsburgh. Columbia, Renn- 
selear Polytechnic, New York University, 
Kansas State Agricultural College, and many 
others for some time have been broadcasting 
subjects gathered from their class rooms. 
And many broadcasters have presented talks 
given by members of various college facul- 
ties. There are many who feel that radio 
can never lend the personal contact that the 
University has always felt to be a necessity 
for instruction. But there are others who 
are quite willing to let radio do what it can 
to broaden the scope of higher education, 
and some of the experiments seem to prove 
that radio has indeed a field here. It is 
maintained by some that broadcasting is 
more a medium for entertainment than in- 
struction, but those who are in charge of the 
various "air courses'* undoubtedly have 
something to say about that. In an early 
number, RADIO BROADCAST will publish an 
article by Major J. Andrew White, the famous 
descriptive broadcaster, which humorously 
shows that radio education is well, not as 
effective as it might be. THE EDITOR 



Having prepared his lecture, he goes to the 
broadcasting studio, that curious muffled 
room where his voice frightens him by meet- 
ing him as he walks in. The room is draped 
with gray cloth, and there are wicker chairs, 
a desk, and floor lamps. And reasonably in- 
conspicuous, are the ever-faithful microphones, 
from which you hear the lecture on "Why 
Read Fiction?" or "Political Parties from 
Washington to Jackson," listeners-in from 
Florida to Washington, and throughout 
Canada eagerly tune-in. 

The light flashes; the man at the announc- 
er's desk calls "all 
right" to his friends 
at the broadcasting 
station ; they return 
the signal; he flashes 
the "Silence" sign at 
the desk, and opens 
the line. The air is 
ready. The instruc- 
tor begins after the 
University announcer 
says, "Good evening! 
This is the University 
of Pittsburgh studio 
of station KDKA, East 
Pittsburgh, Pennsyl- 
vania. This evening, 
Professor Smith, of 
the English Depart- 
ment is going to talk 
to you about 'The 
Contemporary 
Novel."' Then a 
slight pause, and the 
Professor begins his 
talk. This is what 
has been occurring 
regularly at KDKA in 
cooperation with the 
University of Pitts- 
burgh, and is true of 
other broadcasting 
stations in many parts 



47 8 



Radio Broadcast 



of the nation. Some universities have erected 
their own broadcasting stations to give "air 
college courses." Notable among the colleges 
to try this experiment in education is the 
Kansas State Agricultural College whose call, 
KSAC is known to many. 

At Pittsburgh, extensive plans have been 
made for bringing the learning of the college 
class room to the radio listener. A year, or 
more ago, the University of Pittsburgh, 
through its committee on radio extension, 
discussed ways and means of beginning radio 
extension through its 
own studio. Confer- 
ences resulted in an 
agreement of mutual 
responsibility for the 
new venture. The 
University agreed to 
furnish the studio and 
to appoint a full time 
radio manager whose 
business it would be 
to arrange programs 
of consistently high 
merit. The Broad- 
caster installed trans- 
mitting apparatus 
which cost several 
thousand dollars. 

The opening n